File formats and extensions

Elf Qrin's Lab

since 1999

Home

File formats and extensions
v3.0 r23may2016

#

### - Temporary file (Program-dependent format)
#24 - Printer data file for 24-pin matrix printer (LocoScript)
#IB - Printer data file (LocoScript)
#nn - Part of file image (Long)
#SC - Printer data file (LocoScript)
#ST - Standard mode printer definitions (LocoScript)
$$$ - OS/2 archive file (i.e. archives$.$$, keys$.$$) (OS/2)
$$$ - Temporary file ()
$? - ZX Spectrum file in HOBETA format ()
$00 - Pipe file (DOS)
$DB - Temporary file (dBASE IV)
$ED - Editor temporary file (MS C)
$O1 - Pipe file (DOS)
$VM - Virtual manager temporary file (Windows 3.x)
)2( - LHA archiver temporary file (LHA)
??$ - Backup file (P-CAD)
??_ - Microsoft packed file (Expand)
?DK - Disk image (Loaddskf.exe)
?UT - Nonpacked FTN mail (? - flavor) (FidoNet)
!qB - Unfinished qBittorrent download (qBittorrent)
!ut - Unfinished µTorrent download (µTorrent)
___ - Adinf table (Adinf)
EX_ - Compressed executable file (Note: EX could be any first two characters in a file extension (e.g. BM_ for compressed bitmap (BMP), DL_ for compressed library, etc.) Files compressed using this method have been in use on Microsoft software CDs and floppies since around 1995.)
?Q? - Squeeze (CP/M and MS-DOS)
~$~ - Temporary file (1st Reader)
~1~, ~2~, etc. - Backup file (name is constructed with numbered backup option by appending ~, the incremented number, and another ~ after the original name) (GNU coreutils (cp, install, ln, mv ), Emacs)
~?? - Old Backup files (.MNU to .~MN) (Resource Workshop (Borland Delphi))
~H - Cardfile heap (AZZ Cardfile)
µ - Metrowerks Codewarrior project ()
? - THINK C project ()

0-9

0 - Compressed harddisk data (DoubleSpace)
0B - Printer font with lineDraw extended character set (PageMaker)
001, 002, ... - Split parts of a single whole file (FFSJ, HJSplit, JJSplit, split (Unix) (when using numeric suffixes))
1 - Fax ((Many programs))
1 - Roff/nroff/troff/groff source for manual page (cawf2.zip)
123 - Spreadsheet (Lotus 1-2-3 version 9 and version 97)
123dx - CAD drawing file (Autodesk 123D design file, a ZIP file format package containing a .sat file and .png thumbnails.)
15U - Printer font with PI font set (PageMaker)
16 - SYSLINUX Splash Screen Graphic (SYSLINUX, XnView)
1ST - Usually README.1ST text file ()
1TX - 1toX Logipole file ()
2GR - 286 Grabber File (Win)
301 - Fax (Super FAX 2000 - Fax-Mail 96)
386 - Intel 80386 processor driver (Windows 3.x)
386 - Windows virtual device driver (Win)
3DMF - QuickDraw 3D Metafile (QuickDraw)
3DS - 3D Studio Graphics format (3D Studio)
3DT - Database in which the meta-data of a 3D Topicscape is held (3D Topicscape)
3DV - 3-D wireframe graphics by Oscar Garcia (3dv wireframe viewer)
3FX - Effect (CorelChart)
3GA - Mobile Phone Audio (Samsung) ()
3GP - Mobile Phone Video ()
3GR - 386 Grabber File (Win)
3T4 - Binary file converter to ASCII (Util3)
4DB - 4D Structure File (4D)
4DD - 4D Data File (4D)
4DIndy - 4D Structure Index File (4D)
4C$ - Datafile (4Cast/2)
4MD - Musical file ()
4SW - 4DOS Swap File (4DOS)
4TH - FORTH source code file (ForthCMP - LMI Forth)
555 - 16 bit per pixel image file format (5bit per component) (Sierra Entertainment)
602 - Text (fairly simple format, plain text with binary control commands embedded within text lines and special formatting commands on dedicated lines) (Text602 text processor by Software602)
668 - Music (the mixing is always at 12048 Hz) ()
669 - Music (8 channels) (The 669 Composer)
6CM - Music (6 Channel Module) (Triton FastTracker)
75 - 75×75 dpi display font (Ventura Publisher)
7z - A compressed archive file format that supports several different data compression, encryption and pre-processing algorithms (7-Zip)
8 - A86 assembler source code file ()
85 - 85×85 dpi display font (Ventura Publisher)
8BF - Adobe Photoshop compatibile filters/plugins ()
890 - ScanTitling subtitle files ()
8CM - Music (8 Channel Module) (Triton FastTracker)
8M - Printer font with Math 8 extended character set (PageMaker)
8U - Printer font with Roman 8 extended character set (PageMaker)
83p - Executable program for TI-83 Plus Graphing Calculator (TI Connect)
89p - Executable program for TI-89/89 Titanium Graphing Calculator (TI Connect)
8xp - Executable program for TI-83/84 Plus Graphing Calculator (TI Connect)
91 - 91×91 dpi display font (Ventura Publisher)
96 - 96×96 dpi display font ()

A - ADA source code file ()
A - Library (Unix)
A## - AlZip Compressed Files' pieces ()
A11 - Graphics AIIM image file ()
A2W - World file for Alice programming language, version 3.1 ()
A80 - Assembler language source for 8080 ()
AA, AB, ... - Split parts of a single whole file (split (Unix))
AAC - Advanced Audio Coding, a standardized, lossy compression and encoding scheme for digital audio ()
AAF - AutoPatcher file ()
AAF - Advanced Authoring Format, an advanced media wrapper file for professional applications ()
AAS - Animation Play Script (AAPlay)
AB - Android adb Backup (adb)
AB6 - Datafile (ABStat)
AB8 - Datafile (ABStat)
ABC - Alembic - 3D geometry / models (Many Computer Graphics tools, see Alembic (Computer Graphics) for a list.)
ABC - Document (ABC FlowCharter 1.0)
ABC - Music in ABC format (Mainly Video Games)
ABP - Data (ABComp compressed)
ABP - AVS Barcode Profile (AVS Barcode Source)
ABF - Adobe Binary Screen Font (Adobe Systems Software)
ABK - Automatic backup file (CorelDRAW)
ABM - Image PALS album file ()
ABM - Album file (various programs) ()
ABR - Adobe Brush file for PhotoShop (PhotoShop)
ABS - Abstracts (info file) ()
ABS - Data file (Abscissa)
AC - Project backup (Audit Command Language (ACL))
ACA - Project (Project Manager Workbench)
ACB - Archive (ACB)
ACB - see ACMB ()
ACC - Program (DR-DOS - ViewMax) (GEM / resident)
ACCDA - Data (Microsoft Access Database Wizard (Open XML))
ACCDB - Data (Microsoft Access Database (Open XML))
ACCDE - Data (Microsoft Access Database Wizard (Open XML))
ACCDT - Data (Microsoft Access Database Template (Open XML))
ACCDU - Data (Microsoft Access Database Wizard (Open XML))
ACCFT - Microsoft Access Data Type Template[1] (Microsoft Access)
ACE - Archive (ACE)
ACF - Adobe Custom Filter for PhotoShop (PhotoShop)
ACL - Project (Audit Command Language (ACL))
ACL - AutoCorrect List (Microsoft Office)
ACM - Audio Compression Module add-on (Win)
ACMB - Graphics file ()
ACO - Adobe Color Palette (Adobe)
ACT - ACTOR source code file (ACTOR)
ACT - Animations Works Actor (Graphics cell) (Animation Works)
ACT - FoxDoc Action Diagrams (FoxPro)
ACT - Presentation (Action!)
AD - AfterDark screensaver module (AfterDark)
AD2 - ADPCM 2-bit compressed voice file (ZFAX)
AD3 - ADPCM 3-bit compressed voice file (ZFAX)
ADA - Ada source code file ()
ADB - Ada Package Body ()
ADC - Bitmap graphics (16 colors) (Scanstudio)
ADC - Dictionary (Lingvo)
ADD - OS/2 adapter device driver ()
ADF - Amiga Disk File (unADF, UAE, WinUAE etc...)
ADG - Data (ADG 3D Scene)
ADI - Graphics file (AutoCAD)
ADI - Database Index File (Advantage Database Server)
ADICHT - LabChart data acquisition file (ADInstruments)
ADL - MCA adapter description library (QEMM)
ADM - After Dark support file (AfterDark)
ADM - ADEM file format (ADEM)
ADI - Database Memo File (Advantage Database Server)
ADN - Add-in (Lotus 1-2-3)
ADR - After Dark support file (AfterDark)
ADS - Ada Package Specification ()
ADT - WoW geographical map location file (Blizzard Entertainment games (various))
ADT - Datafile for cardfile application (HP NewWave)
ADT - Abrechnungsdatentransfer, an xDT application (Healthcare providers in Germany)
ADT - Dictionary (Lingvo)
ADT - Fax (AdTech)
ADI - Database Table (Advantage Database Server)
ADV - GUS device driver (Gf166.com)
ADX - Document (Archetype Designer)
ADZ - Amiga Disk Zipped (See Amiga Disk File) (GZip)
AEP - After Effects Project File (Adobe After Effects)
AES - File encrypted using the Advanced Encryption Standard (AES) (AES Crypt (Windows, Mac, Linux, Java) and Crypt4All (Android))
AF2 - Flowchart (ABC FlowCharter 2.0)
AF3 - Flowchart (ABC FlowCharter 3.0)
AFI - Truevision bitmap graphics ()
AFL - Font file (for Always) (Lotus 1-2-3)
AFM - Datafile for cardfile application (HP NewWave)
AFM - Type 1 font metric ASCII data for font installer (ATM - many)
AFP - Shape palette (ABC FlowCharter)
AFT - Template (ABC FlowCharter 3.0)
AFW - Workplace (ABC FlowCharter 3.0)
AGR - ArcView ASCII grid ()
AHK - AutoHotkey script file (AutoHotkey)
AI - Adobe Illustrator Artwork (Adobe Illustrator)
AIF - see AIFF ()
AIFC - Audio Interchange File Format with Compression ()
AIFF - Audio Interchange File Format (Convert (c) Villena)
AiM - Asm Text Mode Image File (The Ultimate Draw)
AIN - Archive (AIN)
AIN - Job schedule (AutoIntern)
AIO - APL programming language file transfer format file ()
AIR - Adobe AIR installation package (The Adobe AIR runtime environment)
AIS - Array of Intensity Samples graphics file (Xerox)
AIX - Datafile for cardfile application (HP NewWave)
AKM - "Akai Multitimbral" sample information file (Akai S5000 and S6000 hardware samplers (MS-DOS-based) and compatible software samplers)
AKP - "Akai Program" sample information file (Akai S5000 and S6000 hardware samplers (MS-DOS-based) and compatible software samplers)
ALC - Molecular coordinates (Alchemy, RasMol)
ALG - Activity Log (ARCSOLO)
ALE - Avid Log Exchange (used in film & video editing) (Avid)
ALL - Arts & Letters symbol and font files (Arts & Letters)
ALL - Filelist w/ all files (FRQView)
ALL - Format file for working pages (Always)
ALL - General printer information (WordPerfect for Win)
ALO - Almanac support file ()
ALT - Menu file (WordPerfect Library)
ALZ - AlZip Compressed Files ()
AMD - Maxum chromatograph offline database (Siemens Maxum Chromatograph)
AMF - Music (Advanced Module Format) (DMP)
AMG - Archive (AMGC)
AMG - System image file (ACTOR)
AML - AutomationML (AutomationML Group)
AMPL - AMPL source code file (AMPL)
AMR - Audio format for mobile phones (Nokia, SonyEricsson) ()
AMS - Adobe Monitor Setup calibration file (PhotoShop)
AMS - Music format ()
ANI - Animation cursors for Win (Win95 - WinNT)
ANI - Animation (IconAuthor)
ANM - Animation (Deluxe Paint Animator)
ANIM - Trainz Animation specification file, for example a steam locomotive's connecting rod movements, or water movement on a river or lake motion. (Obsolescent) (Trainz/Auran JET files)
ANN - Annotations of old Windows Help file (Windows 3.0 - XP)
Ann - Multi volume ARJ archive (ARJ)
ANS - ANSI character graphics (animation) file (ANSView)
ANS - ASCII text ANSI character set (NewWave Write)
AOL - America On-line for Windows DLL (Win)
AOS - Add-On Software (Nokia 9000)
AP - Archive (WHAP)
AP - Datafile (Datalex EntryPoint 90)
APC - Printer driver (Lotus 1-2-3)
APD - Printer driver (Lotus 1-2-3)
APE - Monkey's Audio (Lossless) (audio media players)
APF - Printer driver (Lotus 1-2-3)
API - Adobe Printer Ink file for PhotoShop (PhotoShop)
API - Passed parameter file (1st Reader)
API - Printer driver (Lotus 1-2-3)
APK - Android Application (Android)
APL - APL work space format file ()
APL - Support module used by Manugraphics APL products ()
APL - EV-Dos Application File ()
APM - Authorware Macintosh (Authorware)
APP - Add-in application file (Symphony)
APP - Application object file (dBASE Application Generator)
APP - Application (FoxPro)
APP - Application and Application Bundle (Mac OS X)
APP - Executable workflow / macro file (Automator)
APP - Executable application file (DR-DOS - NeXTstep - Atari)
APP - Generated application (FoxPro)
APR - Employee performance review (Employee Appraiser)
APW - Authorware Windows (Authorware)
APX - Appexpert database file (Borland C++ 4.5)
AQF - Analyzer Queries and Filters (Actix)
AR - Argon - for 3D Modeling (Ashlar-Vellum)
AR7 - Archive (AR7)
ARC - Archive (ARC - PKARC/PKXARC - PKPAS - PKUNPAK - QUARK)
ARC - Archive (SQUASH)
ARC - Nintendo proprietary archive format (Various Nintendo games)
ARD - Map (Holux - Alan)
ARF - Automatic Response File ()
ARH - Archivers definitions file (DN)
ARI - Archive (ARI)
ARJ - Archive (ARJ - ARJZ)
ARK - ARC archive (CP/M port of ARC file archiver)
ARK - Archive (QUARK)
ARK - Managing your Money Archive File ()
ARR - Arrangement (Atari Cubase)
ART - Gerber artwork (Cadence Allegro)
ART - First Publisher, Designworks, Greenstreet Draw graphic file (All GST/Greenstreet Draw products)
ART - Graphics (scrapbook) (Art Import)
ART - Graphics format (Another Ray Tracer) (PFS:1st publisher - Art Import)
ARTX - file format (Artisteer)
ARTX - file format (belightsoft Text Art)
ARX - Archive (ARX)
ASC - ASCII text file ()
ASC - Transport armor file (PGP)
ASD - Autosave file (Microsoft Word)
ASD - Presentation (Astound)
ASD - Screen driver (Lotus 1-2-3)
ASD - Spectral Data Set (ASD Inc. RS3 spectral acquisition program)
ASE - Velvet Studio Sample (AWAVE)
ASE - ASCII Scene Export (3D Studio)
ASF - Datafile (APL Shared File) (STATGRAPHICS (APL*Plus/PC))
ASF - Screen font (Lotus 1-2-3)
ASF - Advanced Streaming Format (Compressed Windows audio/video) (Microsoft Corporation)
ASK - SYSGEN answer file (RT-11)
ASH - Assembly language header file (TASM 3.0)
ASI - ASIC language source (ASIC)
ASI - Assembler include file (Turbo C - Borland C++)
ASM - Assembler language source (TASM, MASM, NASM, Yasm, FASM)
ASMX - ASP.NET Web Service (Microsoft Corporation)
ASO - Assembler object (object-oriented) file (Turbo Assembler)
ASP - ASPECT source code file (Procomm Plus)
ASP - Association of Shareware Professionals OMBUDSMN.ASP notice ()
ASP - Active Server Pages of Microsoft.Net (Microsoft Corporation)
ASPX - ActiveX Server Pages of Microsoft.Net (Microsoft Corporation)
ASS - Amalgam Scene Specification (Halo 2 Map Editor)
ASS - Advanced SubStation Alpha (Subtitles) ()
AST - Adobe Color Separation table for PhotoShop (PhotoShop)
AST - Nintendo proprietary music streaming format (Various Nintendo games)
ASV - Autosave File (MATLAB)
ASW - Authorware Star (Authorware)
ASX - Advanced Stream Redirector file, redirects to an ASF file (see ASF) (Microsoft Corporation)
ASZ - Skin (AltDesk)
AT2 - Auto template (Aldus Persuasion 2.0)
AT3 - Atrac 3 Sound/music file (All Sony devices and programs with the Atrac 3+ specification)
ATM - Adobe Type Manager data/info ()
ATN - Adobe Photoshop action (Adobe Photoshop)
ATT - AT&T Group (GCGW)
ATTF - AramOS TypeAtor Text File (AramOS TypeAtor 1.0 (Development State))
ATY - Produced when an association type is exported by 3D Topicscape (3D Topicscape)
AU - Sun/NeXT/DEC Audio file (AWAVE, GoldWave)
AU - Sound (audio) file (Sun Microsystems - Convert (c) Villena)
AUD - Audio file (AudioRack)
AUP - Audacity project file (Audacity)
AUS - Kedit AutoSave file (Kedit)
AUX - Auxiliary dictionary (ChiWriter)
AUX - Auxiliary references (TeX/LaTeX)
AUZ - Ableton Live File (Authorization File for Ableton Live)
AVA - Publication (Avagio)
AVB - AntiViral Toolkit Pro Bases ()
AVI - Audio Video Interleaved animation file (Video for Windows)
AVR - Audio Visual Research (AWAVE)
AVS - Audio Video Software (AVS Video Editor (video editing software))
AVT - AVATAR-coding files (A3E)
AW - Text file (HP AdvanceWrite)
AW - Proprietry Nintendo wave format (Various home console Nintendo games)
AWA - Animations Works Accelerated Movie (Animation Works)
AWD - Microsoft Fax At Work Document (Microsoft Fax At Work)
AWK - AWK script/program (awk, GNU Awk, mawk, nawk, MKS AWK, Awka (compiler))
AWM - Animations Works Movie (as .AVI) (Animation Works)
AWS - Data (APL Workspace) (STATGRAPHICS (APL*Plus/PC))
Ax - Directshow filter file format ()
AXF - ARM Executable Image generated by the ARM tools ()
AXF - "lightweight geodatabase" [1] (ESRI ArcPad)
AXM - Axmedis object (Axmedis Tools)
AZD - Amazon Software Download (Amazon Software Download)
AZW - DRM enabled eBook (All models of Amazon Kindle)
AZW1 - DRM enabled eBook with embedded fonts (All models Amazon Kindle)
AZW2 - Program file (All models of Amazon Kindle excluding Kindle 1)
AZZ - Data file (AZZ Cardfile)

B1 - Archive file format (B1 Free Archiver)
B&W - Black and white graphics file (atari - mac)
B&W - Mono binary screen image (1st Reader)
B - Batch list (APPLAUSE)
B - Grand Theft Auto saved game (Any of the 3D Grand Theft Auto games in either III or IV era.)
B_W - Black and white graphics file (Atari - mac)
B1N - Both mono and color binary screen image (1st Reader)
B30 - Printer font (JLaser - Cordata) (Corel Ventura Publisher)
B3D - Blitz3D files (Blitz3D)
B8 - Raw graphics file (one byte per pixel) plane two (PicLab)
BA - Binary Archive (Scifer Archiver and Compression [External Header Mode])
BAC - Compiled BASIC (RT-11 BASIC-11)
BAD - Bad file (Oracle Corporation - many)
BAD - Animation file (Novalogic)
BAD - File which covers bad blocks on disk volume (not to be moved) (RT-11)
BAK - Backup file ()
BAL - Music score (Ballade)
BALANCE - Balance accounting sheet file (Balance)
BAP - Blaze Audio Wave Information File (BlazeAudio MadCap Software)
BAR - Horizontal bar menu object file (dBASE Application Generator)
BAR - Info Bar for GFX2EXE (GFX2EXE)
BAR - Broker Archive. Compressed file containing number of other files for deployment.[2] (IBM WebSphere Message Broker)
BAS - BASIC language source (QuickBASIC - GW-BASIC - FreeBASIC)
BAT - Batch file (MS-DOS, RT-11)
BB - Database backup (Papyrus Design Group)
BBL - Bibliographic reference file (TeX/BibTeX)
BBM - Brush (Deluxe Paint)
BBP - Playlist (BassBox)
BBQ - BitBeamer Transfer Queue file (BitBeamer)
BBS - Bulletin Board System announce or text info file ()
BBS - Hudson-style messagebase (FTN software)
BC! - Unfinished download (Unfinished BitComet download (a BitTorrent client))
BCD - Boot Configuration Data (Windows Vista and later, Registry Editor)
BCF - Card data (Bingo Card Creator)
BCH - Batch process object file (dBASE Application Generator)
BCH - Datafile (Datalex EntryPoint 90)
BCO - Outline font description (Bitstream Inc.)
BCP - Borland C++ makefile ()
BCT - Backup dictionary (Clarion)
BCW - Environment settings (Borland C++ 4.5)
BDB - Bookends database (Bookends)
BDC - Dictionary (Lingvo)
BDEF - Builder Definition (Websphere Portlet Factory)
BDF - Adobe Glyph Bitmap Distribution Format (Adobe Software)
BDF - Binary update file (BUPDATE.EXE (c) TNT Techn.)
BDF - Bitmap Distribution Format font file (X11)
BDF - Datafile (Egret)
BDM - Videoclip (AVCHD)
BDMV - Blu-ray Video Data Content file (Media players / software that supports Blu-ray structure)
BDR - Border (Microsoft Publisher)
BDT - Dictionary (Lingvo)
BDT - Behandlungsdatentransfer, an xDT application (Healthcare providers in Germany)
BEF - Bleck Encrypted File ()
BEM - BIM Cost estimating file (BIMestiMate)
BEZ - Outline font description (Bitstream)
BF - Brainfuck sourcefile ()
BF2 - Bradford 2 font ()
BFC - Briefcase Win95 (Win95)
BFM - Font metrics (unix/Frame)
BFS - Binary File Storage ()
BFX - Fax (BitFax)
BGA - Bitmap graphics ()
BGI - Borland Graphics Interface device driver (Turbo C - Turbo Pascal)
BH - Blackhole (data compression format)
BI - BASIC include file (Visual Basic - FreeBASIC)
BIB - Bibliography (ASCII) ()
BIB - Database - not compatible with TeX format (Papyrus)
BIB - Literature database (TeX/BibTeX)
BIF - Binary Image Format b&w graphics file (Image Capture board)
BIK - Bink video file (RAD Video) ()
BIM - Building Information Modeling (ArchiCAD / Autodesk Revit)
BIN - Binary file, usually zero-start (.com analog) ()
BIN - SGI Powerflip ()
BIN - Text mode memory dump (The Draw - TUD - ACiDDraw - etc.)
BIO - BioniX Wallpaper playlist file (BioniX Wallpaper Changer)
BIO - OS/2 BIOS ()
BIT - Bitmap X11 ()
BK! - Document backup (WordPerfect for Win)
BK - Faxbook (JetFax)
BK? - Backup file ()
BKC - Backup catalog (Backup4all)
BKF - Backup archive (Windows NTBackup Utility)
BKn - Timed backup file for document window n (WordPerfect for Win)
BKP - Backup file (Write - TurboVidion DialogDesigner)
BKW - Mirror image of font set (FontEdit)
BLD - BLoaDable picture (BASIC)
BLD - SYSGEN Build procedure file (RT-11)
BLEND - Blender3D Project File (Blender)
BLG - Backup Log (ARCSOLO)
BLK - Temporary file (WordPerfect for Win)
BLOB - Unknown (Steam (software) for Win)
BLP - Blizzard Game Picture (Blizzard Entertainment games (various))
BM - BitMap graphics file ()
BM3 - UIQ3 Phone backup ()
BMD - Nintendo proprietary 3D model file (Various Nintendo games)
BMK - Bookmark of old Windows Help file (Windows 3.0 - XP)
BMP - OS/2 or Win graphics format (BitMap Picture) (QPeg - CorelDraw - PC Paintbrush - many)
BMPW - bitmap world-file - geo-references info ()
BMS - Nintendo proprietary MIDI tracker format (Various Nintendo games)
BMT - Ami Pro Button (Ami Pro)
BNA - Data (Atlas Boundary)
BNK - Adlib instrument bank file ()
BNR - Graphics Banner (Banner - Poster)
BOB - File archive for Lego Island 2 (Lego Island 2)
BOD - Stores paths to game files in a BOB archive (Lego Island 2)
BOK - Shamela Library book (Shamela Library Program)
BOO - Book-format (READIBM)
BOO - Compressed file ASCII archive created by BOO (msbooasm.arc) (msbooasm.arc)
BOO - Boo programming language source file (Boo Programming Language)
BOT - Bot files, these go with JKB files (Quake 3 Engine)
BPC - Chart (Business Plan Toolkit)
BPOLY - Data (Prisms binary 3D object)
BPP - Backup application (Clarion)
BPT - Bitmap fills file (CorelDRAW)
BPW - Bitser proprietary encrypted password file (Bitser password manager)
BR - Script (Bridge)
BRD - Eagle Layout File ()
BRD - Tanzzle board file (Tanzzle)
BRD - Cadence Allegro board file (Cadence)
BRF - Braille (Braille embossers and refreshable displays)
BRK - Fax (Brooktrout Fax-Mail)
BRK - The Brake! Mailer REXX script (The Brake!)
BRL - CAD (Ballistic Research Laboratory CAD)
BS - Boot sector file (SYSLINUX)
BS2 - Archive (BS2.EXE)
BSA - Archive (BSArc)
BSC - Compressed Apple II file archive created by BINSCII (BINSCII)
BSC - Database (Source Browser)
BSC - Pwbrmake object file (Microsoft Fortran)
BSP - GoldSource/Source engine map files (Valve Corporation)
BSP - id Tech map files (id Software)
BSS - boot sector (DOS) file (SYSLINUX)
BSS - Casio Phone base (PC-LINK)
BST - BiblioTex file (BiblioTex=bibliography file) (TeX)
BSY - Busy flag (FTN soft)
BTM - Batch-to-memory (quick batch) (4dos -ndos)
BTN - Makeover Button file ()
BTX - backup of 4DOS batch files (_4INST.BTM) (4DOS)
BUFR - Binary Universal Form for the Representation of Meteorological Data ()
BUG - Bugs and Problems ()
BUN - LucasArts Bundle File ()
BUP - Backup file ()
BUT - Button definitions (Buttons!)
BUY - Datafile format (movie)
BVn - Overflow file below insert point in Doc n (WordPerfect for Win)
BWB - Spreadsheet application (Visual Baler)
BWR - Beware (buglist) (Kermit)
BYK - BYK Compressed File (BYK)
BYU - BYU Movie (BYU)
BZ2 - Archive (bzip2)
BZM - Map (Blitzkrieg)
BZN - Map file (Star Trek Armada II Fleet Operations map file)

C-- - C-- language source (Sphinx C--)
C - C language source. Note that on case-sensitive platforms like Unix and with the gcc compiler the uppercase .C extension indicates a C++ source file. (Watcom C/C++, Borland C/C++, gcc and other C compilers)
C - Unix file archive (COMPACT)
C++ - C++ language source ()
C00 - Print file (Ventura Publisher)
C01 - Typhoon wave files (AWAVE)
C32 - COMBOOT Executable (32-bit) (SYSLINUX)
C86 - C source code file (Computer Innovation C86)
CA - Initial cache data for root domain servers (Telnet)
CA? - Borland packed and split file (Borland Installer)
CAB - Win 95 packed file (Win 95)
CAC - dBASE IV executable when caching on/off (see cachedb.bat) ()
CAD - Drawing (BobCAD-CAM)
CAD - Document (Drafix Windows CAD)
CAL - Calendar file (Windows 3.x)
CAL - Spreadsheet format (SuperCalc)
CALS - Computer Aided Acquisition and Logistics ()
CALS - Support Raster Format ()
CAM - Casio Camera ()
CAN - Fax (Navigator Fax)
CAP - Caption (Ventura Publisher)
CAP - Capture file (ProComm - Telix)
CAS - C + ASM language source (Turbo C)
CAT - Catalog (CP Backup - dBASE IV)
CAT - Device driver digital signature (Microsoft Windows)
CAT - Stellarium Star Catalogue (Stellarium)
CATDrawing - Drawing file of CATIA V5 (CATIA V5)
CATPart - Part file of CATIA V5 (CATIA V5)
CATProduct - Assembly file of CATIA V5 (CATIA V5)
CATS - Combined source (ATS)
CBA - Source code (Creative BASIC)
CBC - Fuzzy logic system (CubiCalc)
CBL - COBOL source code file ()
CBM - Compiled bitmap graphics (XLib)
CBR - Comic Book Reader (RAR file) (CDisplay and similar)
CBS - MasterWord button bar configuration file ()
CBT - COMBOOT Executable (incompatible with DOS COM files) (SYSLINUX)
CBT - Computer Based Training (many)
CBZ - Comic Book Reader (ZIP file) (CDisplay and similar)
CC - C++ source code file ()
CC - CC language source (CC)
CCC - Bitmap graphics (native format) (Curtain Call)
CCD - text metadata for CD/DVD images (CloneCD Control File)
CCF - Communications configuration file (Symphony)
CCF - Color Chat file (Color Chat File)
CCH - Chart (CorelChart)
CCITT - CCITT Group 3 and Group 4 Encoding ()
CCL - Communication Command Language file (Intalk)
CCO - BTX Graphics file (XBTX)
CCT - Print Template (BobCAD-CAM)
CD - CD description (DN)
CDA - CD-Audio (Win95)
CDB - Card database (CardScan)
CDB - Main database (TCU Turbo C Utilities)
CDF - Common Data Format ()
CDF - Company Data File (Nominal Small Business Accounting software)
CDF - Computable Document Format (Mathematica)
CDF - Cyberspace Description Format ()
CDF - Graphics (netcdf)
CDK - Document (Atari Calamus)
CDL - CADKey CADL Language (CADKey)
CDM - Disk Drivers NPA (Novell NetWare)
CDM - Music format (compressed) ()
CDO - Music notation (Crescendo Music Notation Editor)
CDR - Vector graphics format (drawing) (CorelDraw!)
CDT - Corel Draw Template File (CorelDraw!)
CDX - Compound index file (Visual FoxPro, Advantage Database Server)
CE - Computer Eyes (Conversion Artist)
CE - Main.ce (The FarSide Computer Calendar)
CEB - Cont. Edge Bitmap (Conversion Artist)
CEF - CA-Clipper Workbench Application (CA Clipper)
CEF - Export File ()
CEF - Compact Embedded Font (Adobe Illustrator)
CEG - Bitmap graphics (Tempra Show - Edsun Continuous Edge Graphics)
CEL - Animation CEL (3D Studio)
CEL - Graphics (Autodesk Animator - Lumena)
CF - Configuration file (imake)
CFA - Audio file (Adobe Premiere Pro)
CFC - ColdFusion Component (Adobe ColdFusion)
CFG - Configuration file ()
CFL - Chart (CorelFLOW)
CFM - ColdFusion Markup Language (Adobe ColdFusion)
CFN - Font data (Atari Calamus)
CFO - C Form Object internal format object file (TCU Turbo C Utilities)
CFP - Fax (The Complete Fax Portable)
CFT - CFast graphics file (Disney Animation Studio)
CGA - CGA display font (Ventura Publisher)
CGI - Common Gateway Interface script ()
CGM - Computer Graphics Metafile vector graphics (A&L - HG - many)
CH - Clipper language header (CA Clipper)
CH3 - Chart (Harvard Graphics 3.0)
CH4 - Presentation (Charisma 4.0)
CHD - Font descriptor (FontChameleon)
CHI - ChiWriter Document (ChiWriter - Chiview)
CHK - Recovered data (DOS CHKDSK)
CHK - Temporary file (WordPerfect for Win)
CHL - Configuration History Log ()
CHM - Compiled Help File (Microsoft Windows, Help Explorer Viewer)
CHML - Encrypted Data File (Krasbit Technologies, Chameleon Imaging Workflow Software)
CHN - Data (Ethnograph 3)
CHP - Chapter file (Ventura Publisher)
CHR - Character set (Turbo C - Turbo Pascal)
CHT - Chart (Harvard Graphics 2.0 - SoftCraft Presenter)
CHT - CHeaT in any program/game (many)
CHT - Interface file for ChartMaster (dBASE)
CHZ - Archive (CHARC)
CIF - Caltech Intermediate Format graphics file ()
CIF - Chapter information (Ventura Publisher)
CIF - Crystallographic Information File (RasMol, Jmol)
CiM - C Text Mode Image File (The Ultimate Draw)
CIX - Database index (TCU Turbo C Utilities)
CKB - Borland C++ 4.x editor keystroke mapping (BCW.EXE)
CL - COMMON LISP source code file ()
CLA - Source (Clarion)
CLASS - Java class file (Java)
CLD - Clipper debugger configuration file (CA Clipper)
CLJ - Clojure source code (Clojure)
CLP - Clip art graphics file (Quattro Pro)
CLP - Clipboard file (Windows 3.x)
CLP - Compiler response file (CA Clipper)
CLP - Graphics format (PCPAINT/Pictor)
CLPI - ClipAV Clip Information file for Blu-ray (Media hardware / software with Blu-ray structure support)
CLPRJ - ClassicLadder project file (ClassicLadder)
CLR - Color binary screen image (1st Reader)
CLR - Color definitions (Photostyler)
CLR - Color scheme (Boxer/2)
CLR - Palette file for GIS format ()
CLS - C++ class definition file ()
CLW - MFC Class Wizard information (Microsoft VC++)
CM - Data file (CraftMan)
CMB - Xtree for Windows Button Bar file ()
CMD - Command (dBASE - Waffle)
CMD - Command Prompt batch file (Microsoft Windows NT based operating systems)
CMD - executable programs (CP/M-86 operating system)
CMD - External command menu (1st Reader)
CMD - OS/2 batch/REXX file (OS/2)
CMF - FM-music file (Creative Music File) ()
CMK - Card (Card Shop Plus)
CMM - CMM script (batch) file (CEnvi)
CMP - Bitmap graphics (Lead CMP compression) ()
CMP - Compressed data (PKWare Inc. data compression library)
CMP - Header file for PostScript printer files (CorelDRAW)
CMP - Photofinish Calibration Map (Photofinish)
CMP - User dictionary (Microsoft Word for DOS)
CMRL - Concise message routing language (DOTGO)
CMS - Content Management System (Any Web Browser)
CMU - Carnegie Mellon University Formats ()
CMV - Animation (CorelMove CorelDraw 4.0) (CorelMove CorelDraw 4.0)
CNC - CNC general program data ()
CND - System generation conditional file (RT-11)
CNF - Configuration (program - printer setup) (program - printer setup)
CNF - Configuration file ()
CNT - contents table of old Windows Help file (Windows 3.0 - XP)
CNV - Temporary file (WordPerfect for Win)
CNV - Winword DLL used as part of an import operation (CNV=converter) (Microsoft Word)
CO - Cobalt - parametric drafting and 3D modeling (Ashlar-Vellum)
COB - Calgari trueSpace2 File Format ()
COB - COBOL source code file ()
COD - Code definition table (UUPC)
COD - Datafile (Forecast Plus - Microsoft Multiplan - StatPac Gold)
COD - file including CODES for any program/game (many)
COD - Printer code definition file (Boxer/2)
COD - Program compiled code (FORTRAN)
COD - Template source file (dBASE Application Generator)
COD - Videotext file ()
COE - Coefficient file (Xilinx ISE)
COF - Animation Control File (Diablo II)
COFFEE - CoffeeScript source code file ()
COL - Color palette (Autodesk Animator - many)
COL - Spreadsheet (Microsoft Multiplan)
COL - DIMACS graph data stores a single undirected graph (text and binary variants) ()
COM - Command (memory image of executable program) (DOS)
COM - Indirect command file (sequence of commands to be executed) (RT-11)
CON - Configuration file (Simdir)
CON - MSTS Consist file (MSTS)
CPC - Compressed image (Cartesian Perceptual Compression)
CPD - Script (Complaints Desk)
CPF - Fax (The Complete Fax)
CPI - ColorLab Processed Image bitmapped graphics file ()
CPI - MS-DOS codepage file (MODE.EXE)
CPL - Control panel file (Windows 3.x)
CPL - Presentation (Compel)
CPMZ - ConPro/Miradi Zipfile (Miradi and ConPro)
CPP - C++ language source (Watcom C/C++)
CPP - Presentation (CA-Cricket Presents)
CPR - Knowledge Access (GCGW)
CPR - Cubase Project File (Steinberg Cubase)
CPS - backup of startup files by QEMM (?) autoexec.cps ()
CPT - Encrypted memo file (dBASE)
CPT - Mac file archive (COMPACT PRO)
CPT - Template (CA-Cricket Presents)
CPZ - Music text file (COMPOZ)
CR2 - Raw image format (Canon digital cameras)
CRA - Advanced crack file (usually text) ()
CRD - Cardfile (Windows 3.x - YourWay)
CRD - Map (Holux - Alan)
CRD - Molecular coordinates (CHARMM, RasMol)
CRDOWNLOAD - Google Chrome download in progress (Google Chrome)
CRF - Cross-reference (Microsoft MASM - Zortech C++, RT-11 CREF)
CRK - Crack file (usually text) ()
CRP - Encrypted database (dBASE IV)
CRS - File Conversion Resource (WordPerfect 5.1)
CRT - Terminal settings information (Oracle)
CRU - Compressed file archive created by CRUSH ()
CRW - CrossWords document file ()
CS - C# source file (C#)
CSD - Compact Shared Document (Dream To Reality)
CSG - Batch file (Submit) (ISIS/w)
CSG - Graph (Statistica/w)
CSM - Borland C++ 4.x precompiled header file (BCW.EXE)
CSP - PC Emcee Screen Image file (Computer Support Corporation)
CSS - Datafile (CSS - Stats+)
CSS - Datasheet (Statistica/w)
CSS - cascading style sheet ()
CSV - Adjusted EGA/VGA palette (CompuShow)
CSV - Comma Separated Values text file format (ASCII) ()
CTC - Control file (PC Installer)
CTF - Character code translation file (Symphony)
CTK - CommonTime Key file (CommonTime software applications)
CTL - Control file (dBASE IV - Aldus Setup)
CTL - BATCH control file (generated by BATCH from .BAT file) (RT-11)
CTT - BATCH Temporary file (RT-11)
CTX - Ciphertext file (Pretty Good Privacy RSA System)
CTX - Course TeXt file (some Microsoft online guides)
CTX - document (Creativyst Table eXchange)
CUF - C Utilities Form definition (TCU Turbo C Utilities)
CUR - Windows resource (cursor image file) (Resource Workshop - WRT - Watcom Resource Editor)
CUT - Graphics format (bitmapped graphics) (dr. Halo)
CV4 - Color file (CodeView)
CVP - Cover page (WinFax)
CVS - Graphics (Canvas)
CVT - Backup file for CONVERTed database file (dBASE IV)
CVW - Color file (CodeView)
CWEB - C Web ()
CWK - Datafile (ClarisWorks, Appleworks)
CXX - C++ source code file (Zortech C++)
CYS - Cytoscape session file (Cytoscape)

D - D Programming Language source file (DMD)
D3V - Video file (Nintendo DS (with ARME, MMCF etc.))
D4D - Data (Draw 4D object)
D4P - Data (Draw 4D Pro object)
D64 - Commodore 64 disk image ()
D88 - Toshiba Pasopeia D88 disk image format (A series of emulators of Japanese computers)
DAA - Direct Access Archive ()
DAE - COLLADA file ()
DAF - Data file (Digital Anchor)
DAT - AMPL data file (AMPL)
DAT - Maxum chromatograph chromatogram (Siemens Maxum Chromatograph)
DAT - LDraw (Sub)Part File, 3D Model (LDraw)
DAT - Document (Microsoft Word Format (old))
DAT - data (RSNetWorx Project)
DAT - Data file in special format or ASCII ()
DAT - Database file (Clarion (programming language))
DAT - Norton Utilities disc image data. It saves Boot sector, part of FAT and root directory in image.DAT on same drive. (Norton Utilities)
DAT - Optical disc image (can be ISO9660, but not restricted to) (cdrdao, burnatonce)
DAT - Video CD MPEG stream ()
DAT - Windows registry hive (REG.DAT Windows 3.11; USER.DAT and SYSTEM.DAT Windows 95, 98, and ME; NTUSER.DAT Windows NT/2000/XP/7) (Microsoft Windows)
DAT - Minecraft game data (Minecraft)
DATS - Dynamic source (ATS)
DAV - Proprietary DVR format (Recorded encrypted video from digital video recorders DVR365 or AlienDVR series[3])
DB$ - Temperature debug info (Clarion Modula-2)
DB$ - Temporary file (dBASE)
DB - Database file (Paradox - XTreeGold - dbvista - Oracle - XoftSpySE - Windows thumbnail cache[4][5])
DB - Configuration (dBASE IV - dBFast)
DB - Multi Edit config (ME)
DB2 - Database (dBASE II)
DB3 - Database (dBASE III)
DBA - Database file (Turbo Prolog - DataEase)
DBA - DarkBasic source code ()
DBC - DataBaseContainer (Visual FoxPro)
DBD - Business data (Business Insight)
DBD - Debug info (Clarion Modula-2)
DBF - Database file (dBASE III/IV - Visual FoxPro - dBFast - DataBoss - DBVista - CA-Clipper - Visual Objects - Alaska Xbase++ - Advantage Database Server)
DBFX - DevBox Database File (Pudince Devbox)
DBG - Debugger script (DOS debug - Watcom debugger)
DBG - Symbolic debugging information (Microsoft C/C++)
DBK - Database backup (dBASE IV)
DBL - DIBOL source file ()
DBM - Datafile (DataEase)
DBM - Menu template (DataBoss)
DBO - Compiled program (dBASE IV)
DBPro - DarkBasicPro Project ()
DBS - Data file used by Managing Your Money ()
DBS - Database in SQL Windows format ()
DBS - Datafile (PRODAS)
DBS - Printer description file (Microsoft Word, Microsoft Works)
DBT - FoxBASE+ style memo (FoxPro 2.x)
DBT - Memo file for database w/same name (dBASE IV - dBFast)
DBW - Windows file (DataBoss)
DBX - DataBeam (GCGW)
DBX - AutoCAD Database (AutoCAD)
DBX - Archive File (Outlook Express)
DC - CAD drawing file (DesignCAD 3000 for Windows)
DC6 - Image file (Diablo II)
DCA - Document Content Architecture text file (IBM DisplayWrite)
DCC - Animation (Diablo II)
DCD - CAD Drawing File (DesignCAD 3DMax for Windows)
DCF - floppy disk image (Disk Copy Fast)
DCH - Schematic Drawing file (DipTrace Schematic Capture)
DCI - Dreamcast Save File (Dreamcast)
DCL - Delphi Control Library (Borland Delphi)
DCM - DCM music module (AWAVE)
DCP - OS/2 device code page (OS/2)
DCS - Bitmap graphics (CYMK format) (QuarkXPress)
DCS - Datafile (ACT! Activity Files)
DCT - Dictionary: used by many programs with program dependent format (Clarion)
DCT - Spell checking dictionary (Harvard Graphics 3.0 - Symphony)
DCT - DataBaseContainer Extension (Visual FoxPro)
DCU - Delphi unit (compiled) (Borland Delphi)
DCW - Walter Machine Programing (Walter Profile Editor)
DCX - Multi-page PCX graphics (common fax format) (Intel - SpectraFAX)
DCX - DataBaseContainer Index (Visual FoxPro)
DD - Macintosh file archive (DISKDOUBLER)
DDA - Data (GLBasic ASCII 3D object)
DDB - Bitmap graphics ()
DDB - Digidesign Database File (Digidesign Pro Tools)
DDD - Building Diagram (Diagramming software)
DDI - Disk image (DiskDupe)
DDP - Device Driver Profile file (OS/2)
DDS - DirectDraw Surface file (Microsoft Flight Simulator, other Microsoft programs)
DEB - DEBUG script (DOS Debug)
DEF - Assembly header file (Geoworks)
DEF - Defaults - definitions ()
DEF - Linker definition file (TLink - WLink...)
DEM - Demonstration ()
DEM - Digital Elevation Model ()
DEM - Graphics file (VistaPro)
DEM - Vista DEM file (Meta.exe VP3)
DES - Ascii text parameter description (AWAVE)
DESKLINK - Windows Explorer Desktop Control (commonly "Desktop (create shortcut).DESKLINK", 0 bytes). Uses a 'special' hidden file extension (NeverShowExt flag inside the Registry), overriding the Windows Explorer option of showing/hiding file extensions. ()
desktop - Desktop Entry (freedesktop.org)
DEV - Device driver ()
DEV - SYSGEN handler build procedure (RT-11)
DEV - Dev-C++ project file (Dev-C++)
DFD - Data Flow Diagram graphic file (Prosa)
DFF - RenderWare model data (e.g. Grand Theft Auto III and later) ()
DFI - Outline font description (Digifont)
DFL - Default program settings (Signature)
DFM - Data Flow Diagram model file (Prosa)
DFM - Delphi form module (Borland Delphi)
DFS - Delight Sound File ()
DFTI - Dynamic Formatted Text and Images (Word Processing) (FlexiWrite)
DFV - Printing form (Word) (Microsoft Word)
DFX - Micrografx Effects DLL ()
DGN - Graphics file (MicroStation)
DGS - Diagnostics ()
DH - Dependency information for .ph (Geoworks)
DHP - Dr. Halo PIC Format graphics file (Dr. Halo II - III)
DHT - Datafile (Gauss)
DI - D Programming Language interface file (DMD)
DIA - Diagraph graphics file (Computer Support Corporation)
DIB - Device Independent Bitmap (rarely used Windows 3.0 bitmap; Win - OS/2)
DIC - Dictionary (e.g. from WinWord) ()
DICOM - Digital Imaging and Communications in Medicine (DICOM) bitmap (DICOM Software (XnView))
DIF - Borland patch data file (Borland patch)
DIF - Data Interchange Format (Visicalc)
DIF - OS/2 V2.2 Display Information File (OS/2)
DIF - Output from Diff command - script for Patch command ()
DIF - SRCCOM, BINCOM output file (RT-11)
DIG - Digilink (AWAVE)
DIG - Sound Designer 1 audio file (AWAVE)
DIP - Graphics ()
DIP - Watcom debug info processor (WatcomDebugger)
DIP - PCB Drawing file (DipTrace PCB Layout)
DIR - Dialing directory file (Procomm Plus)
DIR - Directory file (VAX - CPS Backup)
DIR - Movie (MacroMind Director 4.x)
DIR - Directory listing file (RT-11)
DIS - Distribution file (VAX Mail)
DIS - Thesaurus (CorelDraw)
DIZ - Description file (Description In Zip) ()
DJVU - DJVU Document Format, a format similar to PDF but with higher compression rates at the same quality. (DJVU)
DKB - Raytraced graphics (DKBTrace)
DL - Animation format (Italian origin) (Display - DL Viewer)
DLD - Lotus 1-2-3 ()
DLF - Dialogue Live Format (Produced by Exstream Dialogue and edited by Dialogue Live Editor)
DLG - Dialog resource script file (Microsoft Windows SDK)
DLG - Dialog resources (DN)
DLG - Windows SDK dialog editor data file ()
DLG - Windows SDK dialog editor data file ()
DLL - Dynamic-link library (Windows 3.x - OS/2)
DLL - Export/import filter (CorelDRAW)
DLM - Microsoft File Transfer Manager (Microsoft File Transfer Manager)
DLP - Data (DAQLab)
DLS - Setup (Norton Disklock)
DMF - Music format (Delusion Digital Music File) (Delusion)
DMF - DeleD files ()
DMG - Apple Disk Image (Mac OS X (Disk Utility),)
DMO - Demo (Derive)
DMP - Dump file (e.g. screen or memory) ()
DMP - DUMP utility output file (RT-11)
DMS - Amiga file archive (DISKMASHER)
DNG - Digital Negative (DNG), a publicly available archival format for the raw files generated by digital cameras (At least 30 camera models from at least 10 manufacturers, and at least 200 software products)
DNT - data (RSNetWorx Project)
DO - Java servlet file (Web browser (Various))
DOC - A Document, or an ASCII text file with text formatting codes in with the text; used by many word processors (Microsoft Word and others)
DOCM - Microsoft Word 2007 Master document (Microsoft Word 2007)
DOCX - Office Open XML Text document (Microsoft Word)
DOF - Delphi project options file (Borland Delphi)
DOG - Screen file (Laughing Dog Screen Maker)
DOH - Dependency information for .poh (Geoworks)
DOR - Roland Digital audio file (Roland)
DOS - External command file (1st Reader)
DOS - Network driver (e.g. pkt_dis.dos) ()
DOS - OS/2 V3 SVGA PMI-File (Svga.exe)
DOS - renamed system files (AUTOEXEC.BAT, COMMAND.COM, CONFIG.SYS,DBLSPACE.BIN, DRVSPACE.BIN, IO.SYS, MSDOS.SYS) of previous MS-DOS version (Windows 95, 98, ME (dual-boot feature))
DOS - Text file containing DOS specific info ()
DOT - Line-type definition file (CorelDRAW)
DOT - Microsoft Word document template (Microsoft Word)
DOTX - Office Open XML Text document template (Microsoft Word)
DOX - Text file (MultiMate 4.0)
DOZ - Description Out of Zip (VENDINFO)
DP - Calendar file (Daily Planner)
DP - Data file (DataPhile)
DPR - Default project- and state-related information (Borland C++ - Delphi - C)
DPF - Bareboard PCB CAD/CAM format (Ucamco)
DPX - Digital Moving Picture Exchange ()
DRP - Web3D File (Web3D)
DRS - Display Resource (WordPerfect for Win)
DRV - Driver ()
DRW - Designer vector graphics file (Designer - MicroGraphix)
DS - TWAIN Data Source (Any twain-source must supply one xxx.ds file)
DS1 - Map file (Diablo II)
DS4 - Vector graphics (Micrografx Designer 4.x)
DSC - Celestia Deep Space Catalog file (Celestia)
DSC - Description file ()
DSC - Discard file (Oracle)
DSD - Database (DataShaper)
DSF - Data Storage Format (Golden Helix)
DSF - Delusion Digital Sound File (Delusion)
DSK - Desktop configuration (BP - DN - BC++ - TP)
DSK - Disk Drivers (Novell NetWare)
DSK - Logical disk file (RT-11)
DSM - Digital Sound Module (DSI)
DSN - Design (Object System Designer)
DSP - Display parameters (Signature)
DSP - Dynamic Studio Professional Module (Dynamic Studio)
DSP - Graphics display driver (Dr. Halo)
DSP - Norton viewer DLL (Win)
DSP - Visual Studio 6 project file (Microsoft Visual Studio)
DSR - Driver Resource (WordPerfect for Win)
DSS - Screensaver file (DCC)
DSS - Digital Speech Standard (Sound) (Digital Soup)
DSS - SQL Script for .Time Framework (Exaktime)
DST - Tajima Embroidery Format (Embroidermodder)
DST - WAIN (Scanner spec) data source DLL (Win)
DSV - Nintendo DS battery save (DeSmuME, DraStic)
DSW - Borland C++ 4.x desktop layout file (BCW.EXE)
DSY - DAISY container file (ADAKTA.EXE)
DT1 - Tile file (Diablo II)
DT2 - msn-emoticon (paint)
DT_ - Data fork of a Macintosh file (Mac-ette)
DTA - Data file (Turbo Pascal - PC-File - Stata)
DTB - Database Backup for .Time Framework (Exaktime)
DTF - Database file (PFS - Q&A)
DTL - Django template language (djangoproject)
DTM - DigiTrekker music module (AWAVE)
DTO - data (Directory Toolkit output)
DTP - Desk Top Publishing Document (Timeworks / greenstreet Publisher3/ Greenstreet Publisher 4.5)
DTP - Page Magic 2.0 publication (Page Magic 2.0 upgrades to Greenstreet Publisher)
DTP - Publication (Publish-It! upgrades to Greenstreet Publisher)
DTS - Torque Game Engine model format ()
DVC - Data (Lotus 1-2-3)
DVDPROJ - iDVD project file (iDVD (Apple iLife '08))
DVI - DeVice Independent document (TeX)
DVP - DESQView run-file (DESQView)
DVP - Device parameter file (AutoCAD)
DW2 - Drawing (DesignCAD for DOS, & DesignCAD for Windows)
DWB - Coryphaeus Software Designers Workbench (CSD)
DWC - Archive (DWC)
DWD - DiamondWare Digitized file (AWAVE)
DWG - Drawing (AutoCAD, IntelliCAD, PowerCAD, Drafix, etc.)
DWZ - DVD MovieFactory for TOSHIBA Project File, Designer vector graphics file (Designer - MicroGraphix or TOSHIBA)
DX - Text file (DEC WPS/DX format - DEC WPS Plus)
DXF - Dialogue Exchange Format (Exstream Dialogue)
DXF - Drawing Interchange File Format vector graphics (AutoCAD, IntelliCAD, PowerCAD, etc.)
DXN - Fax (Fujitsu dexNET)
DXP - SpotFire data (TIBCO Spotfire)
DXP - ISO creation project file (CD Burner XP Pro)
DYLIB - Dynamic Library (Mac OS-X)
DYN - Data (Lotus 1-2-3)

E - E language source code (E)
E## - EnCase Evidence File chunk (EnCase Forensic Analysis Suite entity)
E00 - ArcInfo interchange file (GIS software)
E2D - 2-dimensional vector graphics file (Editor included in JFire)
EAS - Extended file attributes (OS/2)
EAR - Enterprise archive (archive)
EBA - Source code (Emergence BASIC)
EBD - versions of DOS system files (AUTOEXEC.BAT, COMMAND.COM, CONFIG.SYS, WINBOOT.SYS, etc. ) for an emergency boot disk (Windows 98, ME)
EBJ - Error-checking object file (Geoworks)
EBQ - CITE standard electronic BQ exchange file ()
EC - Error checking preprosessed Goc source code (Geoworks)
EC - Source code (eC)
ECC - Error-checking file (dvdisaster)
ECE - Escenic Contentng Engine dynamic page (Escenic)
ECMS - Status document (ECMerge)
ECMT - Template document / Session (ECMerge)
ED5 - EDMICS (GCGW)
EDA - Ensoniq ASR disk image (AWAVE)
EDE - Ensoniq EPS disk image (AWAVE)
EDF - European data format (Medical timeseries storage files)
EDF - Exchequer Document Format (IRIS Software)
EDK - Ensoniq KT disk image (AWAVE)
EDL - EDL (Premiere)
EDQ - Ensoniq sq1,2/ks32 disk image (AWAVE)
EDS - Ensoniq SQ80 disk image (AWAVE)
EDT - Default settings (VAX Edt editor)
EDT - Ensoniq TS disk image (AWAVE)
EDT - External editors definitions (DN)
EDV - Ensoniq VFX-SD disk image (AWAVE)
EEB - Button bar for Equation Editor (WordPerfect for Win)
EFA - Ensoniq ASR file (AWAVE)
EFA - Encrypted File Archive ()
EFE - Ensoniq EPS file (AWAVE)
EFE - Ensoniq EPS instrument file (AWAVE)
EFK - Ensoniq KT file (AWAVE)
EFQ - Ensoniq SQ1/SQ2/KS32 file (AWAVE)
EFS - Ensoniq SQ80 file (AWAVE)
EFT - Ensoniq TS file (AWAVE)
EFT - High resolution screen font (ChiWriter)
EFV - Ensoniq VFX-SD file (AWAVE)
EFX - Fax (Everex EFax)
EGA - EGA display font (Ventura Publisher)
EKA - Internal data files (Borland's Eureka)
EL - ELISP source code file (Emacs)
ELB - Synergy/DE library ()
ELC - byte Compiled ELISP code (Emacs)
ELFO - ElsterFormular ()
ELI - Archive (ELI)
ELT - Event list text file (Prosa)
EMAIL - Outlook Express Email Message (Windows Live Mail, Outlook Express, Notepad)
EMAKER - E language source code (maker) (E)
EMC - Striata Reader Encrypted Document Format ()
EMD - ABT Extended MoDule (AWAVE)
EMF - Microsoft Enhanced Metafile ()
EML - Stationery Template (Outlook Express)
EMU - Terminal emulation data (BITCOM)
ENC - Encoded file - UUENCODEd file (Lotus 1-2-3 - uuexe515.exe)
ENC - Music (Encore)
END - Arrow-head definition file (CorelDRAW)
ENFF - Extended Neutral File Format ()
ENG - Dictionary engine (Sprint)
ENG - English documentation ()
ENG - Graphics file (charting) (EnerGraphics)
ENV - Envelope or Environments ()
ENV - Enveloper macro (WOPR)
ENV - Environment file (WordPerfect for Win)
EOT - Embedded Open-Type ()
EP - GUI wireframe/prototype project (Prikhi Pencil, Evolus Pencil)
EPA - Award BIOS splash screen (Award BIOS, XnView)
EPD - Publication (Express Publisher)
EPI - Document (Express Publisher)
EPI - Encapsulated PostScript graphic file ()
EPS - Encapsulated PostScript (Graphics format) (CorelDraw - PhotoStyler - PMView - Adobe Illustrator - Ventua Publisher)
EPUB - Electronic Publication - (e-Reader format) (Okular (Linux) - Apple iBooks - Sony Reader - Adobe Digital Editions - Calibre (LMW))
EQN - Equation filE (WordPerfect for Win)
ERD - Entity Relationship Diagram graphic file (Prosa)
ERL - Erlang source code file ()
ERM - Entity Relationship Diagram model file (Prosa)
ERR - Compiler/linker error report ()
ESCPCB - Data file of "esCAD pcb", PCB Pattern Layout Design Software (esCAD pcb provided by Electro-System)
ESCSCH - Data file of "esCAD sch", Drawing Schematics Diagram Software (esCAD sch provided by Electro-System)
ESH - Extended Shell batch file ()
ETH - Document (Ethnograph 3)
ETF - Encrypted Text File. Used in some security programs. ()
ETW - Proprietary format from EnterTech for the MagicSing/Mic Karaoke product line. (Enter-Tech)
ETX - Structure-enhanced text for some ascii text browsers ()
EUI - Ensoniq EPS family CD image (AWAVE)
EVT - Events descriptions ()
EVT - Windows Event log file (Microsoft Windows NT 4.0 - XP; Microsoft Event Viewer)
EVTX - Windows Event log file XML structured (Microsoft Windows Vista, 7, 8; Microsoft Event Viewer)
EVY - Document (WordPerfect Envoy)
EWD - Document (Express Publisher for Windows)
EX3 - Device driveR (Harvard Graphics 3.0)
EXB - Audio File (E-MU Systems Emulator X Sampler File)
EXC - Exclude file for Optimize (do not process) (QEMM) (QEMM)
EXC - REXX source code file (VM/CMS)
EXE - Directly executable program (DOS)
EXF - Exactal Exchange File (CostX)
EXF - Excute file (OnHand PC)
EXM - MSDOS executable, system-manager compliant (HP calculator) (HP calculator)
EXP - Drawing File format (Drawing Express)
EXP - Melco Embroidery Format (Embroidermodder)
EXP - Protected mode EXE by PharLap Software (PharLap)
EXP - Exports Library File (VisualStudio)
EXS - Audio File (Apple Logic Pro EXS instrument)
EXT - Extensions descriptions file ()
EXX - Intermediate file by MsgPut (IBM LinkWay)
EZW - easyOFFER document file[6] (easyOFFER by Reagency Systems Corp.)
EZF - Fax (Calculus EZ-Fax)

F - Archive (FREEZE)
F - Forth language source code file (Forth development systems)
F - Fortran language source code file (in fixed form) (Many Fortran compilers)
F01 - Fax (perfectfax)
F03 - Fortran language source code file (in free form) (Many Fortran compilers)
F2R - Farandole Linear Module (Farandole)
F3R - Farandole Blocked Linear Module (Farandole)
F4 - Fortran IV source code file ()
F4A - Flash Video F4V with only audio (see also SWF) (Adobe Flash)
F4B - Flash Video F4V audiobook (see also SWF) (Adobe Flash)
F4P - Flash Video F4V with digital rights management (see also SWF) (Adobe Flash)
F4V - A container format for Flash Video that differs from the older FLV file format (see also SWF) (Adobe Flash)
F77 - Fortran language source code file (in fixed form) (Many Fortran compilers)
F90 - Fortran language source code file (in free form) (Many Fortran compilers)
F95 - Fortran language source code file (in free form) (Many Fortran compilers)
F96 - Fax (Frecom FAX96)
FAC - see FACE ()
FACE - Usenix FACE graphics file ()
FAL - Falcon script source (Falcon)
FAM - Famtasia Famicom image format (Famtasia)
FAQ - Frequently Asked Questions text file ()
FAR - Music format (Farandole Composer Module) (Farandole)
FAS - Macsyma compiled program ()
FAX - Fax (raster graphics in CCITT format) (most Fax programs)
FB - Backup files (Fifth Generation Systems FastBack Plus)
FBM - Fuzzy Bitmap ()
FBW - HP Backup and Recovery Manager (HP Backup)
FC - Spell checking dictionary (Harvard Graphics 2.0)
FCM - Binary file patch file (forward compression) (jlpak10.zip)
FCP - Final Cut Pro project file (Final Cut Pro)
FD - Declaration file (Microsoft Fortran)
FD - Field offsets for compiler (DataFlex)
FD - Front Door' resource files (FD)
FDB - Font Definition Block (Ming library)
FDS - fwNES Famicom Disk System image (fwNES)
FDS - Headerless Famicom Disk System image ()
FDW - Form (F3 Design and Mapping)
FDX - Screenplay (Final Draft)
FE - Data (Surface Evolver 3D surface)
FEB - Button bar for Figure Editor (WordPerfect for Win)
FEI - Fatal Error Infotable (Geoworks)
FES - File produced when a fileless occurrence in 3D Topicscape is exported to Windows (3D Topicscape)
FF - Intelligont FIAS format ()
FF - Outline font description (Agfa Compugraphics)
FFE - Front Fareast Famicom image format ()
FFF - Fax (defFax)
FFI - Atech FastFont (AllType) ()
FFIVW - File Format for the Interchange of Virtual Worlds ()
FFT - Dca/FFT Final Form Text text file (DisplayWrite) ()
FFT - DCA/FFT Final Form Text text file (DisplayWrite)
FH3 - Vector graphics (Aldus FreeHand 3.x)
FH4 - Vector graphics (Aldus FreeHand 3.x)
FI - Interface file (Microsoft Fortran)
FIF - Fractal Image Format file ()
FIG - Figure File (MATLAB)
FIL - Table Data (Audit Command Language (ACL))
FIL - File template (Application Generator)
FIL - Filelist ()
FIL - Files list object file (dBASE Application Generator)
FIL - Mirror. FIL is the name given to the saved FAT by the mirror program included in some versions of DOS and in PCTools (MS-DOS -)
FIL - Overlay (WordPerfect)
FIL - File which was moved to the Virus Vault by AVG ()
FILE - A generic Windows file ()
FILM - Filmkey film file (Filmkey Player)
FIN - Print-formatted text file (Perfect Writer - Scribble - MINCE)
FIO - Aldus PhotoStyler graphics filter ()
FIO - Image PALS viewer DLL ()
FIT - File Index Table (WindowsNT)
FIT - see FITS ()
FIT - Fityk Script (Fityk)
FITS - Flexible Image Transport System (astronomy software)
FIX - Patch file ()
FKY - Macro file (FoxPro)
FLA - Source material for Flash applications (see SWF) (Adobe Flash)
FLAC - Audio codec, Audio file format ()
FLAME - Fractal configuration file (Apophysis)
FLB - Format library (Papyrus)
FLC - Animation format FLIC >320x200 (AAPlay - Autodesk AniPro)
FLD - Folder (Charisma)
FLI - Animation format FLIC 320x200 (Autodesk Animator)
FLI - TeX font library (EmTeX)
FLM - Film Roll (AutoCAD/AutoShade)
FLP - Flstudio project file (Fruity Loops (FlStudio))
FLP - FLP Designer layout file (FLP Designer)
FLT - Data/file conversion filter (or overlay) (Alsud, Microsoft Word)
FLT - Filter file (Micrografx Picture Publisher)
FLT - MultiGen Flight ()
FLT - Support file - graphics filter (Asymetrix ToolBook)
FLX - Animation format ()
FLX - Compiled binary (DataFlex)
FLV - A container format for Flash Video (see also SWF) (Adobe Flash)
FM - Database (FileMaker Pro)
FM1 - Spreadsheet format overlay (Lotus 1-2-3 release 2.x)
FM3 - Device driver (Harvard Graphics 3.0)
FM3 - Spreadsheet (Lotus 1-2-3 release 3.x)
FMB - File Manager Button bar (WordPerfect for Win)
FMF - Font or icon file (IBM LinkWay)
FMK - Makefile (Fortran PowerStation)
FMO - Compiled format file (dBASE IV)
FMT - Format file (dBASE IV - FoxPro - Clipper 5 - dBFast)
FMT - Gate3 format file ()
FMT - Style sheet (Sprint)
FMV - Full Motion Video file ()
FN3 - Font file (Harvard Graphics 3.0)
FND - Files searching properties (Win95)
FNI - FileNet Native Document (FileNet)
FNK - FunkTracker music module (AWAVE, FunkTracker)
FNM - Fannie Mae Residential Loan Data (RLD) format for mortgage submission to DO/DU (Desktop Originator)
Fnn - DOS screen text font - height nn pixels (fntcol13.zip)
FNT - Font file (many)
FNX - Inactive font (Exact)
FO1 - Font file (Borland Turbo C)
FO2 - Font file (Borland Turbo C)
FOG - Fontographer Database File (Fontographer3.5)
FOL - Folder of saved messages (1st Reader)
FON - Log of all calls (Procomm Plus)
FON - Terminate phonebook (Terminate - Terminator - Telix)
FON - Windows bitmapped font file (Win)
FONT - Font data (unix)
FOP - Freedom of the Press graphic file ()
FOR - Form (WindowBase)
FOR - Fortran language source file (many)
FOT - Installed Truetype font (Windows Font Installer)
FOX - Foxbase executable (precompiled .prg) (FoxBase)
FP - Final Page file (FoxPro for DOS)
FP - Tiff file (TIFF/IT P1)
FP - Video file (DVICO/TVIX MPEG1 video file)
FP3 - Database (FileMaker Pro)
FP4 - Database (FileMaker Pro)
FP5 - Database (FileMaker Pro)
FP7 - Database (FileMaker Pro)
FPC - Catalog (FoxPro)
FPD - TMT Pascal compiled unit (TMT Pascal)
FPM - Configuration file (FoxPro for MacIntosh)
FPT - Foxpro memo field tables (FoxPro)
FPU - Configuration file (FoxPro for Unix)
FPW - Floorplan drawing (FloorPLAN plus for Windows)
FPW - Configuration file (Visual FoxPro)
FPX - FlashPix Bitmap Image File (FlashPix)
FR? - Packed mail (FTN software)
FR3 - Renamed dBASE III+ form file (dBASE IV)
FRF - FontMonger Database file (FontMonger)
FRG - Uncompiled report file (dBASE IV)
FRL - GP-Forth library (GP-Forth)
FRM - Registration or other form ()
FRM - Report file (dBASE IV - Clipper 5 - dBFast)
FRM - Visual Basic Form (Visual Basic)
FRO - Compiled report file (dBASE IV)
FRP - Form (PerForm PRO Plus - FormFlow)
FRS - Screen Font Resource (WordPerfect for Win)
FRT - Additional (FPT) report description file (FoxPro)
FRT - GP-Forth source file (GP-Forth)
FRX - Main (DBF) report description file (Visual FoxPro)
FRX - Visual Basic binary program file (Visual Basic)
FSA - Applied Biosystems Genetic Analysis data file (GeneScan)
FSIM - Simulation File Format (Loudsoft)
FSL - Form (Paradox for Windows)
FSM - Farandole Composer WaveSample (Farandole)
FSPROJ - Habanero Firestarter project (Habanero Firestarter)
FST - Linkable program (dBFast)
FST - Temporal database file (GTKWave data file)
FSTICK - Temporal database file (Flash Joystick)
FSX - Data (Lotus 1-2-3)
FTD - Falcon dynamic template (Falcon)
FTM - Font file (Micrografx)
FTS - Full text search index of old Windows Help file (Windows 3.0 - XP)
FTXT - text (Cloanto text document)
FTP - Configuration (FTP Software PC/TCP)
FUK - Map File (Postal 2)
FW - Database (FrameWork)
FW2 - Database (Framework II)
FW3 - Database (Framework III)
FWEB - Fortran WEB ()
FX - On-line guide (FastLynx)
FXD - Phonebook (FAXit)
FXP - Foxpro executable (precompiled .prg) (Visual FoxPro)
FXS - FAX Transmit Format graphics file (WinFax)
FYF - FileLoc (FyTek, Inc.)

G - Data chart (APPLAUSE)
G16 - GoldED for DOS compiled config (GOLDED.EXE)
G3 - Group 3 Fax (Netpbm,ImageMagick,XnView)
G3D - Glest model file (G3D viewer)
G3P - Grand Prix 3 car physics (Grand Prix 3 data)
G8 - Raw graphics file (one byte per pixel) plane three (PicLab - Cubicomb Picturemaker)
GAF - Globa Game Engine audio format (Globa Game Engine)
GAM - Fax (GammaFax)
GAMEPROJ - Gamesalad game project format (GameSalad)
GB - Game Boy ROM (Nintendo)
GB1 - Game Maker backup file (can also be GB2, GB3, etc.) ()
GBA - Game Boy Advance ROM (Nintendo)
GBC - Game Boy Color ROM (Nintendo)
GBL - Genesis Bitmap Layout (Genesis Bitmap)
GBL - Global definitions (VAXTPU editor)
GBL - Global module in Basic programs (Basic)
GBP - Genesis Bitmap Pattern (Genesis Bitmap)
GBS - GBS meta data (Generic Build Support (GBS))
GBR - Gerber format (PCB CAD/CAM)
GBR - GIMP brush ()
GC - Savegame (Star Wars: Battlefront II Galactic Conquest save file)
GC1 - Lisp source code (Golden Common Lisp 1.1)
GC3 - Lisp source code (Golden Common Lisp 1.3)
GCA - IBM GOCA (GCGW)
GCD - Graphics (ROBLOX)
GCD - General content descriptor (Wireless devices)
GCD - Generic Cadd drawing (Generic Cadd, Visual Cadd)
GCF - Game cache file (Steam content delivery system)
GCH - GNU preprocessed C++ header file (GNU C++ compiler)
GCI - Nintendo GameCube save file (Nintendo GameCube)
GCX - Graph file (Mac OS X Grapher)
GD3 - Game Doctor Super NES ROM image ()
GDF - General Data Format for Biomedical Signals (Biomedical signal processing, Brain Computer Interfaces)
GDF - Dictionary file (GEOS)
GDF - Geographical Data Format (Various mapping software)
GDF - IBM Graphics Data Format (Legacy IBM systems)
GDL - Data (ArchiCAD model)
GDS - McDonnell-Douglas Things ()
GDT - Gerätedatentransfer, an xDT application (Healthcare providers in Germany)
GE - GEcho config file (GEcho)
GED - GEDCOM (Genealogy data exchange)
GED - Native format for all A&L products since 1983 (Arts & Letters)
GED - GoldED for DOS compiled config file (GOLDED.EXE)
GED - Graphics editor file (EnerGraphics)
GED - Game Editor Data / project file (Game Editor)
GEM - Vector graphics file (GEM - Ventura Publisher)
GEN - Compiled template (dBASE Application Generator)
GEN - Generated text (Ventura Publisher)
GEO - Geode (Geoworks)
GEO - GEOS specific file (application) (GEOS)
GEO - GoldED for OS/2 compiled config file (GED2.EXE)
GEX - GEcho config file (GEcho)
GFB - Compressed GIF image created by GIFBLAST (gifblast.exe)
GFO - SGI Radiosity ()
GFT - Font (NeoPaint)
GFT - GEM-translator font file ()
GFX - Instant Artist graphics Files (Instant Artist)
GFX - PCBoard @X-coded colorful text (GFX2COM - GFX2EXE)
GHO - Norton Ghost File (first file) (Symantec)
GHS - Norton Ghost File (split file) (Symantec)
GHW - GHDL Wave file (GHDL/GTKWave data file)
GIB - Chart (Graph-in-the-Box)
GIB - GIMP animated brush ()
GID - Global index of old Windows Help file (Windows 3.0 - XP)
GIF - Compuserves' Graphics Interchange Format (bitmapped graphics) (QPeg - Display - CompuShow)
GIW - Presentation (Graph-in-the-Box for Windows)
GKH - Ensoniq Disk Image (VFX, SD, EPS, ASR, TS) (Ensoniq)
GKS - Graphics Kernel System ()
GL - Animation format (grasprt.exe, PV)
GL - Animation (GRASP GRAphical System for Presentation)
GLB - Global module in Basic programs ()
GLM - Datafile, KernelCAD model (Glim, KernelCAD)
GLO - Global module in Basic programs ()
GLS - Datafile (Across)
GLY - Winword Glossary (Microsoft Word)
GM6 - GameMaker Editable file as of version 6.x (Game Maker)
GM81 - GameMaker Editable file as of version 8.1.x (Game Maker)
GMD - GameMaker Editable file up to version 5.x (Game Maker)
GMF - CGM graphics file (APPLAUSE)
GMK - GameMaker Editable file as of version 7.x or 8.x (Game Maker)
GML - GameMaker GML script file (Game Maker)
GML - Geography Markup Language File (Geography Markup Language)
GMOD - Data (Golgotha 3D model)
GMP - Geomorph tile map (SPX)
GMS - Ghost Mouse Script ()
GMS - Gesture and Motion File Formats ()
GMT - Gene Matrix Transposed ()
GMT - data (RFactor car physics)
GMX - GameMaker:Studio Editable File as of 1.x (Game Maker)
GO - Go source code file (Golang)
GOC - Goc source code file (Geoworks)
GOE - GOES graphic file ()
GOH - Goc header file (Geoworks)
GP - Geode parameter file (Geoworks Glue)
GP4 - data (Grand Prix 4 car physics)
GP5 - Guitar Pro 5 song (Guitar Pro 5)
GPH - Graph (Lotus 1-2-3/G)
GPK - Omnigo program package ()
GPX - GPS eXchange Format ()
GR2 - Screen driver (Windows 3.x)
GRA - Datafile (SigmaPlot)
GrADS - Metafile ()
GRAFFLE - OmniGraffle graph file ()
GRASP - Graphical System for Presentation ()
GRB - T-FLEX CAD file (Top Systems)
GRB - MS-DOS Shell Monitor file (MS-DOS 5)
GRD - Drivers for GRX (graphics library) (GRX (c) Free Soft. Found.)
GRDNT - Image format used in the core of some very obscure customized operating systems to represent gradients; see also SCTOR ()
GRE - data (Grenoble Thermal ellipsoids Plot Program)
GRF - Graph file (Graph Plus, DPlot, and Charisma)
GRFT - Graph definition text file (SELDM Postprocessor)
GRIB - Gridded Binary ()
GRN - Drivers for GRX (graphics library) (GRX (c) Free Soft. Found.)
GRP - Group file (Windows 3.x - Papyrus)
GRP - Pictures group (PixBase)
GRY - Graphics format (RAW GREYz) ()
GS - Script written in Google Apps Script, used for automating tasks across online Google products (Google Apps Script)
GS1 - Presentation (GraphShow)
GS3 - data (GameStarter)
GSA - data (Microsoft Office Groove Space Archive)
GSD - Vector graphics (Professional Draw)
GSM - Raw GSM 6.10 audio stream (AWAVE)
GSP - Geometer's Sketchpad ()
GSW - Worksheet (GraphShow)
GTA - data (Microsoft Office Groove Tool Archive)
GUP - PopMail ()
GV - GrandView outline file ()
GVO - Data (GFXFX Vector Object)
GWI - Groupwise File (Local saved Email)
GXL - Graphics library (Genus)
GXK - Secure Data encryption Format (Galaxkey)
GZ - Archive (GNU zip - WinZipNT)
GZR - data (GunZ action replay)

H! - On-line help file (Flambeaux Help! Display Engine)
H! - Pertext database (HELP.EXE)
H-- - C—language header (Sphinx C--)
H - Header file (usually C language) (Watcom C/C++)
H++ - Header file (C++)
HA - Archive (HA)
HAL - Data file (Hyper Access Lite OS/2)
HAM - Disk Drivers NPA (Novell NetWare)
HAM - Hold And Modify (Deluxe Paint image file)
HAP - Archive (HAP3)
HBC - Compressed Archive File (Shrink Algorithm) (Hyperbac)
HBC - Compressed Archive File (Shrink Fast Algorithm) (Hyperbac)
HBE - Compressed, Encrypted Archive File (Shrink & AES256-bit Encryption) (Hyperbac)
HBK - MathCAD handbook (MathCAD)
HC - Header file ()
HCG - Document (HCLab)
HCGS - Document (HCLab)
HDD - data (disk image)
HDD - HotDisc Designer label ()
HDF - Amiga Hard Disk Image ()
HDF - Help file (Help Development Kit)
HDF - Hierarchical Data File graphics file (SDSC Image Tools)
HDL - Alternate download file listing (Procomm Plus)
HDMP - heap dumpfile ()
HDR - Datafile (Egret)
HDR - Message header text (Procomm Plus - 1st Reader)
HDR - PC-File+ Database header ()
HDR - SPOT image file ()
HDS - Hierarchical Data System ()
HDW - Vector graphics (Harvard Draw)
HDX - Help index (AutoCAD - Zortech C++)
HDZ - Amiga Zip compressed Hard Disk Image ()
HEP - Novell Help Librarian Data File (Novell NetWare)
HEX - Hex dump ()
HFI - HP Font Info file (GEM)
HGL - Highlight groups definitions (DN)
HGL - HP Graphics Language graphics file ()
HH - C++ header file ()
HHH - Precompiled header file (Power C)
HHP - Help information for remote users (Procomm Plus)
HI - Game high scores table ()
HIN - Molecule (HyperChem)
HIS - History of executing/viewing/editing (DN)
HIS - Yard Information File (FYM)
HKM - Stores sound in a bitmapped graphics file ()
HLB - Help library (VAX)
HLP - old Windows Help file (Windows 3.0 - XP, Help Explorer Viewer)
HLX - Multi Edit help file (MultiEdit 5.0)
HLZ - Multi Edit packed help file (MultiEdit)
HMI - Music format (MIDI) ()
HMM - Alternate Mail Read option menu (Procomm Plus)
HMP - Music format (MIDI) ()
HMP - Hump Setup File - Obsolete as of version 2.4 (See SET and SWT files) (FYM)
HNC - CNC program files Heidenhain (?) dialog ()
HOF - Hall Of Fame (game scores) ()
HOM - CAD Software Data File (PLXHOME)
HP - Printout file for HP printers/plotters (HP/GL) ()
HP8 - ASCII text HP Roman8 character set (NewWave Write)
HPF - HP LaserJet fonts (PageMaker)
HPG - see HPGL ()
HPGL - Plotter file vector graphics (Hewlett-Packard Graphics Language) (AutoCad - Harvard Graphics)
HPI - Font information file (GEM)
HPJ - Help project (Microsoft Help Compiler for Windows - HC.EXE)
HPK - Archive (HPACK)
HPM - Alternate Main menu for privileged users (Procomm Plus)
HPM - EMM text (HP NewWave)
HPM - High Performance Map (Quaestor 1.x)
HPP - C++ header file (Zortech C++ - Watcom C/C++)
HPPCL - Hewlett-Packard Printer Control Language ()
HQX - Archive (ASCII Mac) (BINHEX)
HRF - Graphics file (Hitachi Raster Format) ()
HRM - Alternate Main menu for limited/normal users (Procomm Plus)
HRZ - Graphics format (SSTV)
HS2 - Monochrome image (Postering)
HSC - 2-op FM music (HSC tracker - hscplay.exe)
HSH - Disk image hash file (DriveSnapshot)
HSI - Handmade Software Inc. graphics file almost JPEG (Image Alchemy)
HST - History file (Procomm Plus)
HTM - see HTML ()
HTML - Hypertext Markup Language (WWW) (Netscape - Mosaic - many)
HTX - Hypertext file ()
HUS - Husqvarna Viking Embroidery Format (Embroidermodder)
HVE - Hive file[1] (Microsoft)
HWA - Hollywood applet (Hollywood)
HWD - Presentation (Hollywood Designer)
HWP - Hangul Word Processor Document (Hangul (word processor))
HWS - Hollywood script (Hollywood)
HXM - Alternate Protocol Selection menu for all users (Procomm Plus)
HXS - Microsoft Help 2 compiled help file (Microsoft Windows, Help Explorer Viewer)
HXX - C++ header file ()
HY1 - Hyphenation algorithms (Ventura Publisher)
HY2 - Hyphenation algorithms (Ventura Publisher)
HYC - Data (WordPerfect)
HYD - Hyphenation dictionary (WordPerfect for Win)
HYP - Archive (HYPER)

I - Preprocessor output file (Borland C Preprocessor)
I - SWIG interface file (SWIG)
IAK - Internet Access Kit (OS/2)
IAM - Assembly file (Autodesk Inventor)
IAX - Bitmap graphics (IBM Image Access eXecutive) ()
IAX - data (InstallAnywhere.NET project)
IBG - PDS graphic file ()
IBM - Archive (Internal IBM only) (ARCHDOS)
IBRO - Robot save file (Incredibots 2)
ICA - Bitmap graphics (Image Object Content Architecture) ()
ICB - Targa ICB bitmap graphics (many raster graphics editors)
ICC - ICC configuration ()
ICE - LHA Archive (Cracked LHA (old LHA), Total Commander)
ICFE - IceFormula Equation Workspace (Penguin George)
ICFM - IceFormula Math Workspace (Penguin George)
ICM - ICC configuration ()
ICN - ICON source code file ()
ICO - Icon file (ICONEDIT.EXE; Microsoft Windows)
ID - Disk identification file ()
IDB - IDA database (IDA)
IDB - VC++ Minimum Rebuild Dependency File (Visual C++)
IDC - IDA C language source (IDA)
IDE - Borland C++ 4.x IDE project (BCW.EXE)
IDF - MIDI instrument description ()
IDS - IDA imported names format (IDA)
IDW - Vector graphics (IntelliDraw)
IDW - Drawing file (Autodesk Inventor)
IDX - Index (many - FoxPro; also unrelated Quicken file format)
IFD - Form (JetForm Design)
IFF - Interchange Format File (IFF) (EA Software - Convert (C) Villena - Amiga)
IFF - Sun TAAC Image File Format (SDSC Image Tool)
IFP - Script (KnowledgeMan)
IFS - Fractal image compressed file (Yuvpak)
IFS - Iterated fractal system file (IFS Creation Kit, Apophysis)
IFS - Installable file system (OS/2)
IGES - Initial Graphics Exchange Specification ()
IGF - Inset Systems (GCGW)
IGC - Flight tracks downloaded from GPS devices in the International Gliding Commission's prescribed format ()
IHP - Watcom help file (whelp.exe)
IHS - Inbound History (Bink/+)
IIW - Power Point Image Importer Wizard ()
IL - hDC Designer Icon Lin dll format ()
ILB - Data (Scream Tracker)
ILG - data (LaTeX Index Generation log)
ILK - Outline of program's format (Microsoft ILink incremental linker)
IM - Auran Jet indexed mesh file (Trainz)
IM8 - Sun Raster graphics file ()
IMA - Mirage vector graphics (EGO - Chart - Autumn)
IMA - Disk image (WinImage)
IMG - ADEX graphic file ()
IMG - Disk Image (NC 5.0)
IMG - GEM bitmapped graphics file (Ventura)
IMG - Image for Windows/Image for DOS Disk image (TeraByte, Inc. dba TeraByte Unlimited)
IMG - Vivid IMG file ()
IMI - image (Magellan Meridian map)
IMI - image (Magellan eXplorist map)
IMP - Spreadsheet (Lotus Improv)
IMQ - Image presentation (ImageQ)
IMZ - Disk image (WinImage)
IN - Design II for Windows INput file ()
IN - autoconf INput file ()
IN$ - Installation file (HP NewWave)
IN3 - Input device driver (Harvard Graphics 3.0)
INB - Test script (Vermont HighTest)
INC - Include file (several programming languages)
IND - Data Index (dBASE IV)
INDD - InDesign Document (Adobe InDesign)
INF - Information text file (ASCII) ()
INF - Install script ()
INF - OS/2 hypertext help system file (VIEW.EXE)
INF - Type 1 LaserJet font information file (soft font installers)
INFO - GNU info reader (output from Texinfo) (info (Unix))
INFO - Icon Data (Amiga) ()
INGR - Intergraph Raster File Format ()
INI - Initialization file ()
INK - Pantone reference fills file (CorelDRAW)
INS - Data (WordPerfect)
INS - Ensoniq Instrument File (Ensoniq)
INS - Installation script (1st Reader)
INS - Instrument music file (Adlib) ()
INT - Borland Interface Units ()
INT - Program saved in Internal (semi-compiled) format (Signature)
INT - Source of Borland interface module ()
INX - Index (Foxbase)
IO - Archive (CPIO)
IOB - 3d graphics database in TDDD format (Imagine)
IOC - Organizational chart (Instant ORGcharting!)
ION - 4DOS DESCRIPT.ION file (file descriptions like long filenames, comments, or extended attributes) (4DOS, NDOS, 4OS2, 4NT, TC, TCC, VC, DN, ODN, NDN, Windows Commander, Total Commander, XnView, ACDSee, Newsbin Pro, V, as well as some CUI LIB-based applications)
IP - Immortal Player file (Immortal Player)
IPA - Apple iOS Application (iPhone, iPod touch, iPad)
IPC - Intellitec Program Configuration - used to configure vehicle electronics (Intellitec)
IPF - Interchangeable Preservation Format (SoftPres)
IPG - iPod game file (iTunes and iPod)
IPH - Hi-Res Image (InterPaint)
IPL - Pantone Spot reference palette file (CorelDRAW)
IPN - Intecplan project (Intecplan Business Plan Software)
IPS - IPS Patching Format (International Patching System)[citation needed] (Rom hacking community)
IPSW - iOS firmware file (iPhone, iPod touch, iPad, Apple TV)
IPT - Part file (Autodesk Inventor)
IPT - MultiColor Image (InterPaint)
IRRMESH - static irrMesh files ()
IRS - Resource (WordPerfect) standard.irs (WordPerfect)
IRT - Data (IRIT 3D model)
IRTR - Graphicon-2000 Interactive Real-Time PHIGS ()
ISD - Spelling Checker dictionary (RapidFile)
ISH - Archive (ISH)
ISMA - Output Video file (Islam Abusa'a Software)
ISO - ISO-9660 table (see: List of ISO image software)
IST - Digitrakker Instrument File (AWAVE)
IT - Impulse Tracker music file (Impulse Tracker)
IT - Settings (intalk)
ITF - Technical indicator, trading system or market scan source code file (ProRealTime)
ITF - Interface file (JPI TopSpeed Pascal)
ITL - iTunes music library ()
ITN - Itinerary file (TomTom PNDs)
ITT - IconTweaker Theme ()
IV - SGI Inventor ()
IV-VRML - Inventor VRML Format ()
IVE - OpenSceneGraph 3D model ()
IVI - Image file (ImmerVision)
IVL - Lensflare file (ImmerVision)
IVP - Panorama file (ImmerVision)
IVU - User Interface file (ImmerVision)
IW - Presentation flowchart (IconAuthor - HSC InterActive)
IWA - Text file (IBM Writing Assistant)
IWB - Information WorkBench (Prodeo)
IWD - Call of Duty Map - Game Data Archive (Activision, Inc.)
IWP - Text file (Wang)
IX - data (dtSearch index)
IZT - Izl binary token file (IZL)

J2C - JPEG 2000 image ()
JAM - Jam messagebase (FTN software)
JAM - Jam music score (Jam)
JAR - Java archive (JAR, Java Games and Applications)
JAS - see JASC ()
JASC - Graphics format (JASC) ()
JAV - see JAVA ()
JAVA - Java source code file ()
JBD - Datafile (SigmaScan)
JBIG - Joint Bilevel Image Group ()
JBX - Project file (Project Scheduler 4)
JCN - JobClock.Net Synch File ()
JEF - Janome Embroidery Format (Embroidermodder)
JET - Fax (Hybrid JetFax)
JFF - see JFIF ()
JFIF - JPEG File Interchange Format ()
JIF - see JFIF ()
JMS - Music format (JMusic file) (UltraForce)
JNLP - Java Network Launching Protocol (Java Web Start)
JOB - Gravostyle engraving pattern file (Gravostyle/Gravograph)
JOB - QUEUE output file (RT-11)
JOR - Journal file SQL ()
JOU - Journal backup (VAX Edt editor)
JP2 - JPEG 2000 image ()
JPC - Graphics (Japan PIC)
JPEG - Joint Photographic Experts Group graphics file format (QPeg - FullView - Display)
JPG - Joint Photographic Group ()
JPS - backup of startup files (AUTOEXEC.BAT, CONFIG.SYS, 4DOS.INI) by installation of 4DOS (JP Software) (4DOS)
JRE - Java Runtime Environment (Java)
JRN - JMP journal (JMP)
JS - JavaScript file (script in HTML pages)
JSON - JSON (JavaScript Object Notation) (Ajax)
JSONLD - JSON-LD, a JSON-based Serialization for Linked Data ()
JSP - JavaServer Pages (Dynamic pages running Web servers using Java technology)
JTF - Fax (Hayes JT Fax)
JTF - Graphics (TIFF file with JPEG compression) ()
JVX - Data (JavaView object)
JW - Text document (JustWrite)
JWL - Library (JustWrite)
JZZ - Spreadsheet (Jazz)

K2A - Data (Prince of Persia 3D object)
K3D - Description of macro language 3DS (3DS)
KAP - Map Info Sea Chart ()
KAR - Music format (Karaoke) (ITune 1000.Corp)
KAR - Precompiled .prg for KARAT (Rus. FOX+ 2.0)
KB - Keyboard script (Borland C++ 4.5)
KB - Program source (Knowledge Pro)
KB - K-Brief in XML format (TCC's Set-Based Thinking™ Tools)
KBA - K-Brief Attachment (TCC's Set-Based Thinking™ Tools)
KBASIC - Source (KBasic)
KBD - Keyboard mapping (LocoScript - Signature - Procomm Plus)
KBM - Keyboard mapping (Reflection 4.0)
KBS - K-Brief in Encrypted format (TCC's Set-Based Thinking™ Tools)
KBZ - K-Brief in Compressed format (TCC's Set-Based Thinking™ Tools)
KCL - Lisp source code (Kyoto Common Lisp)
KD - Koara Document (Koara)
KDB - KeePass 1.x database file (KeePass)
KDBX - KeePass 2.x database file (KeePass)
KDC - Kodak Digital Camera (graphics) (PhotoEnhancer by PictureWorks)
KEP - (unknown) ((unknown))
KEX - Kedit Macro File (Kedit)
KEY - Datafile (Forecast Pro)
KEY - Keynote presentation file (Keynote (Apple iWork '08))
KEY - Keyboard macros ()
KEY - OS/2 archive .key-file (i.e. OS2.KEY) (OS/2)
KEY - Security file e.g. Shareware Registration info ()
KEY - Keynote (iOS devices, Macintosh)
KFN - complex music format|[2] (Karafun Karaoke(R))
KFX - Kofax Group (GCGW)
KIT - Power Chords drum kit file (Power Chord)
KMC - KatzReview's MegaCrammer ()
KML - Kedit Macro Library (Kedit)
KML - Keyhole Markup Language (Google Earth)
KMY - data (KMyMoney)
KMZ - Keyhole Markup Language (Zip compressed) (Google Earth)
Knn - Database key file (Clarion)
KNO - Personal Knowbase data file (Personal Knowbase)
KO - linux kernel object file (linux kernel)
KODU - Kodu game save file (Kodu Game Lab)
KPL - source code (Phrogram)
KPP - Toolpad (SmartPad)
KPS - IBM KIPS bitmap graphics ()
KR1 - Kurzweil 2000 sample file (AWAVE)
KR2 - Kurzweil 2000 sample file (AWAVE)
KRZ - Kurzweil K2000 File (Kurzweil)
KS - Source code (KonsolScript Document)
KS3 - Data (3D Forgastest Editor object)
KSM - Pfaff Embroidery Format (Embroidermodder)
KTU - Know The Unknown Online Service Packs (Unknownsoft)
KWB - Knowledge WorkBench (Prodeo)
KYB - Keyboard mapping (FTP Software PC/TCP)

L - LEX source code file ()
L - Linker directive file (WATCOM wlink)
L - LISP source code file ()
LA0 - Datafile (SCUMM index file)
LAB - Datafile (NCSS - SOLO)
LAB - Mailing labels (Q+E for Microsoft Excel)
LAN - Erdas image file ()
LAN - LAN Drivers (Novell NetWare)
LANG - Language file (Minecraft, Skype)
LAS - Lasso File (Lasso Programming Language File)
LASSO - Lasso File (Lasso Programming Language File)
LAY - Word chart layout (APPLAUSE)
LBG - Label generator data (dBASE IV)
LBL - Label (dBASE IV - Clipper 5 - dBFast)
LBM - Graphics format (Amiga) (Pic-view - Deluxe Paint)
LBM - Linear bitmap graphics (XLib)
LBO - Compiled label (dBASE IV)
LBR - .LBR Archive (for CP/M and MS-DOS using the LU program)
LBR - Display driver (Lotus 1-2-3)
LBT - Additional (FPT) label description file (FoxPro)
LBX - Main (DBF) label description file (FoxPro)
LCF - Linker Control File (Norton Guides compiler)
LCH - Chart (IBM Works for OS/2)
LCK - Lockfile (Paradox)
LCL - Data (FTP Software PC/TCP) ()
LCL - Data (FTP Software PC/TCP)
LCN - Lection (WordPerfect)
LCS - Datafile (ACT! History Files)
LCW - Spreadsheet (Lucid 3-D)
LD - Long Distance codes file (Telix)
LDA - Absolute binary file (load image) (PDP-11, RT-11)
LD1 - Overlay file (dBASE)
LDB - Data filer database (IBM Works for OS/2)
LDB - Overlay file (Microsoft Access)
LDF - Data filer form (IBM Works for OS/2)
LDF - Library definition file (Geoworks Glue)
LDT - Labordatenträger, an xDT application (Healthcare providers in Germany)
LE - DOS/4GW executable image (DOS/4GW PM 32X DOS Extender)
LES - Lesson (check *.cbt) ()
LEV - Level file (NetHack 3.x)
LEX - Dictionary (Microsoft Word - Lexicon)
LFL - LucasArts resource file ()
LFD - LucasArts resource file (LucasArts games)
LFT - Laser printer font (ChiWriter)
LG - Logo procedure definitions (LSRHS Logo)
LGO - Logo for header and footer (SuperFax)
LGO - Startup logo code (Windows 3.x)
LHA - LHA Archive (LHA/LHARC, Total Commander)
LHW - Amiga archive (LHWARP)
LIB - Library file (several programming languages)
LIC - License file used by some programs to put their license on disk ()
LIF - Archive ()
LIF - CA Clipper packed file (CA Clipper installer)
LIF - Logical Interchange Format data file (Hewlett-Packard)
LIM - Archive (LIMIT)
LIN - Line types (AutoCAD)
LIS - Listing (VAX)
LIT - Microsoft E-book file (Microsoft Reader)
LIT - Web3D File (Web3D)
LIX - Log file (history) (Audit Command Language (ACL))
LJ - Text file for HP LJ II printer ()
LL - LLVM Assembly Language (llvm)
LL3 - LapLink III related file (document) (LapLink III)
LM - Auran Jet LOD mesh table (text file to control LODs) (Trainz)
LMP - Doom lump (data file, commonly "demo" recordings) (Doom - Doom2)
LNG - Language definition file ()
LNK - Linker response file (.RTLink)
LNK - Linker script ()
LNK - Windows 95 shortcut (Windows 95)
LNK - Windows XP shortcut (Windows XP)
LOD - Load file ()
LOG - Log file (Numerous systems)
LOM - 3D Model (Lock On: Modern Air Combat)
LPC - Printer driver (TEKO)
LRC - Lyrics data ()
LRF - Linker response file (Microsoft C/C++)
LRF - Unencrypted BroadBand eBook file (Sony Librie eBook reader)
LRP - Report (IBM Works for OS/2)
LRS - Language Resource File (WordPerfect for Win)
LRX - Encrypted BroadBand eBook file (Sony Librie eBook reader)
LS - LiveScript source code file ()
LSA - Lightscape Technologies ASCII ()
LSB - Lightscape Technologies Binary ()
LSC - Leostream Connect file (Leostream Corporation)
LSP - LISP source code file (Xlisp, AutoLISP)
LSS - Spreadsheet (Legato - IBM Works for OS/2)
LSS - SYSLINUX Splash Screen Graphic (SYSLINUX, XnView)
LST - Aus. BOM Hourly weather Data ()
LST - Filelist (FRQView)
LST - Keyboard macro (1st Reader)
LST - List file (archive index - compiler listfile) ()
LST - Listing (e.g. source code) ()
LST - Map list (Holux - Alan)
LST - Spool file (Oracle)
LST - SLP output file (RT-11)
LTA - Data (LithTech ASCII 3D object)
LTM - Form (Lotus Forms) (Lotus)
LUA - Lua script file (Microsoft Visual C++, Notepad++)
LUW - label data file (Labels Unlimited for Windows)
LUX - 2D and 3D graphics data file (Foliomap and Spectramap)
LUZ - 3D graphics data file (Spectramap CUDA)
LWD - Text document (LotusWorks)
LWO - Lightwave Object Format ()
LWP - Word processor (IBM Works for OS/2, Lotus Wordpro)
LXF - Lego Exchange Format (Lego Digital Designer data file)
LXO - Luxology scene (modo3D software)
LXT - Temporal database file (GTKWave data file)
LY - LilyPond Notation File (LilyPond)
LYR - Lyrics (ASCII) ()
LYT - Document Layout file (Adminsoft Accounts)
LZ - Archive (Lzip)
LZD - Difference file for binaries (LDiff 1.20)
LZH - LHA Archive (LHA/LHARC, Total Commander)
LZS - LHA Archive (LARC, Total Commander)
LZW - Archive (LHWARP)
LZX - Amiga Archive (LZX)

M - Mathematica Package File (Mathematica)
M - MATLAB M-File (MATLAB)
M - Mercury Source File (Mercury)
M - Source code (Objective-C)
M2 - WoW Model Object file (Blizzard Entertainment games (World of Warcraft/Warcraft series))
M2TS - MPEG 2 Transport Stream (Various media playback devices / software)
M3U - M3U playlist file (Winamp, XMMS)
M3U8 - Unicode version of M3U playlist file (UTF-8) (Winamp, XMMS)
M4 - m4 macro file ()
M4A - Advanced Audio Coding ()
M4r - iPhone ringtone (iTunes and iOS devices)
M7P - Multilizer 2007 and 2009 localization project file (Multilizer)
M8M - 8MAM8 Model File ()
MAFF - Mozilla Archive Format (Mozilla Firefox (with add-on))
MAI - Mail (VAX)
MAK - Makefile ()
MAK - Project file (VB – VC ++)
MAN - User guide (manual) ()
MANAGER - Accounting data file (Manager – free accounting software)
MAP - Color palette file ()
MAP - Format data (Micrografx Picture Publisher)
MAP - Linker map file ()
MAP - Map file (usually created by compilers) ()
MAP - Map (Atlas MapMaker)
MAP - Network map (AccView)
MAP - Game map for Duke Nukem 3D ()
MAR - Assembly program (VAX Macro)
MAR - Microsoft ARchive (MSN Explorer (possibly other Microsoft products too))
MAR - Mozilla ARchive (Mozilla Updater (used to house binary updates to products))
MAS - SmartMaster set (Freelance Graphics)
MAT - Data (MATLAB)
MAT - Microsoft Access Table (Microsoft Access)
MAX - MAX source code file ()
MAX - Pfaff Embroidery Format (Embroidermodder)
MB - Memo field values for database (Paradox)
MBK - Multiple index file backup (dBASE IV)
MBP - Metadata (.mobi (Mobipocket))
MBR - Master Boot Record File (GRUB)
MBX - Mailbox data (Eudora/ZERBERUS)
MCA - Minecraft "Anvil" world format (Minecraft 1.2 and onward)
MCC - Configuration file (Mathcad)
MCD - MathCad file (MathCad)
MCF - Font file (Mathcad)
MCF - Photo book or photo calendar layout file (FotoInsight Designer)
MCF - Multimedia Container Format (predecessor of Matroska) ()
MCI - MCI command script (Media Control Interface)
MCL - Multi Edit macro library (Multi Edit)
MCL - Cartesian manipulator for laser systems ()
MCP - Application script (Capsule)
MCP - Printer driver (Mathcad)
MCR - Minecraft saved world "region" file (Minecraft (up to 1.1))
MCW - Text file (MacWrite II)
MD - Archive (mdcd10.arc)
MD - Text file found on github on many project readme.pm (Mark Down)
MD2 - Quake 2 Model File (id Software)
MD3 - Quake 3 Model File (id Software)
MD5 - Doom 3 and Quake 4 Model File (id Software)
MD5 - MD5 checksum (md5sum,Total Commander)
MDA - Data (Microsoft Access)
MDA - Microsoft Access system database (Microsoft Access)
MDB - Microsoft DataBase (Microsoft Access)
MDF - Media Descriptor File, binary files in which the actual disc (CD/DVD) data is stored (Alcohol 120%)
MDF - Master Data File, a Microsoft SQL Server file type (Microsoft SQL Server)
MDF - Measurement Data Format, a binary file format for vector measurement data (automotive industry, developed by Robert Bosch GmbH)
MDL - Model (3D Design Plus or Simulink)
MDL - Spreadsheet (CA-Compete!)
MDL - GoldSrc Model File (Quake-Based Engine) (Valve Corporation)
MDL - Source Engine Model File (Valve Corporation)
MDL - Quake 1 Model File (id Software)
MDL - Nintendo GameCube Luigi's Mansion Model (Nintendo)
MDM - Modem definition file (TELIX)
MDMP - Mini dumpfile ()
MDR - Microdrive file (ZX Spectrum emulator by g.a.lunter)
MDS - Midi Session (Sound Imp.)
MDT - Data table (Microsoft ILink incremental linker)
MDX - Multiple index file (dBASE IV)
MDZ - Text description of music module (Cubic Player – Cross-View)
ME - MultiEdit configuration (MultiEdit)
ME - Text file READ.ME ()
MEB - Macro Editor bottom overflow file (WordPerfect Library)
MEC - MECCA source (Maximus)
MED - Macro Editor delete save (WordPerfect Library)
MED - Music format (MED/OctaMED)
Mediawiki - Wiki markup (most wikis)
MEM - Macro Editor macro (WordPerfect Library)
MEM - Memory variable save file (dBASE IV – FoxPro – Clipper)
MEM - Memos datafile (Clarion)
MEM - Mnemosyne database (Mnemosyne; other spaced repetition software)
MEQ - Macro Editor print queue file (WordPerfect Library)
MER - Macro Editor resident area (vakioalue) (WordPerfect Library)
MES - Macro Editor work space file (WordPerfect Library)
MES - Message ()
MET - Document (Omnipage Pro)
MET - Macro Editor top overflow file (WordPerfect Library)
MET - OS/2 graphics metafile (PICVIEW.EXE)
MEU - Menu group (DOS Shell)
MEX - Macro Editor expound file (WordPerfect Library)
MEX - MEX file (executable command) (Matlab)
MF - Metafont file (TeX)
MFA - Source code file (Multimedia Fusion 2 / The Games Factory 2)
MFF - MIDI (Cakewalk, MTPro 4)
MFM - Music format (DMP)
MGF - Font (Micrografx)
MGF - Materials and Geometry Format ()
MGX - Designer 4.1 Drawing (Designer 4.1)
MHT - Web Archive Single File ()
MIB - Snmp MIB file ()
MID - Standard MIDI file (music synthetizers, Winamp)
MIDI - See MID ()
MIFF - Magick Image File Format ()
MII - Datafile (MicroStat-II)
MIME - Message in MIME format (RFC822) ()
miniUSF - Nintendo proprietary MIDI file format for the Reality Signal Processor (Nintendo 64) (Nintendo 64 games)
MIO - MyInfo topic (Milenix MyInfo)
MIS - Mission, used by many games ()
MIT - Mitsubishi Embroidery Format (Embroidermodder)
MIX - Object file (Power C)
MK - Makefile ()
MKE - Makefile (Microsoft Windows SDK)
MKG - Makefile ()
MKI - Graphics format (Japan MKI) ()
MKI - Japanese graphics MAKIchan format (MagView 0.5)
MKS - Data (TACT)
MKV - Matroska Multimedia Container (Media Player Classic, Windows Media Player, Matroska Splitter)
ML3 - Project (Milestones 3.x)
MLB - Macro library file (RT-11, Symphony)
MLI - 3DS Materials Libraries (3D Studio)
MLRAW - Data (Moonlight Creator RAW format 3D object)
MLV - LabVIEW MathScript ()
MM - Text file (MultiMate Advantage II, FreeMind mind map file (XML))
MM - Source code (Objective-C++)
MMF - Mail message file (Microsoft Mail)
MMM - Multimedia movie file, RIFF RMMP format (MacroMind Director 3.x)
MMO - Memo writer file (RapidFile)
MMP - Output video format from Bravado board ()
MN - MuPAD Pro Notebook (Workspace file of MuPAD (integrated in Matlab))
MND - Menu source (AutoCAD Menu Compiler)
MNG - Map (DeLorme Map'n'Go)
MNT - Additional (FPT) menu description file (FoxPro)
MNT - Menu memo (FoxPro)
MNT - Surface metrology or image analysis document (MountainsMap)
MNU - Advanced macro file (HP NewWave)
MNU - Menu (AutoCAD Menu Compiler – Norton Commander – Signature)
MNU - Microsoft Mouse menu (for DOS apps) ()
MNX - Compiled menu file (AutoCAD)
MNX - Main (DBF) menu description file (FoxPro)
MNY - Account book (Microsoft Money)
MO? - Packed mail (FTN software)
MOB - Device definition file (PEN Windows)
MOBI - eBook (Mobipocket)
MOD - AMPL model file (AMPL)
MOD - Modula language source ()
MOD - MODULA-2 source code file (Claridiv id="MDZ"> MDZon Modula-2)
MOD - Module—used by Windows for DLL which implement DOS support (Win)
MOD - Music format (Amiga module) (DMP – ST – MDP – VP)
MOL - MOD4WIN PlayList (Mod4Win)
MOL - MDL Molfile (RasMol)
MOL2 - Tripos’ Sybyl MOL2 Format (SYBYL, RasMol)
MON - SYSGEN monitor build procedure (RT-11)
MON - Monitor description (ReadMail)
MOP - MOPAC input file (MOPAC, RasMol)
MOV - Animation format (Mac) (QuickTime)
MOV - Movie file (AutoCAD AutoFlix)
MP2 - Mpeg audio file (Winamp, xing)
MP3 - MPEG audio stream, layer 3 (AWAVE, CoolEdit(+PlugIn), Winamp, many others)
MP4 - multimedia container format, MPEG 4 Part 14 (Winamp)
MPA - MPEG audio stream, layer 1,2,3 (AWAVE)
MPC - Calendar file (Microsoft Project)
MPC - Musepack audio ()
MPEG - multimedia containter format, video, audio (MPEG Player, Winamp)
MPG - see MPEG ()
MPKG - Multipackage installer script (Mac OS X)
MPL - MediaRack Midi Playlist (MediaRack)
MPM - MathPlan macro (WordPerfect Library)
MPP - Project file (Microsoft Project)
MPPZ - MagicPlot project file (MagicPlot)
MPQ - Mo'PaQ Archive (Blizzard games)
MPR - Generated executable menu file (FoxPro)
MPR - Multilizer 5.x and 6.x localization project file (Multilizer)
MPR - Command & Conquer: Red Alert 2 map file (Red Alert 2)
MPT - Bitmap graphics (Multipage TIFF) ()
MPV - View file (Microsoft Project)
MPX - Compiled executable menu file (FoxPro)
MPX - Video format ()
MPZ - Miradi Project Zipfile (Miradi)
MRB - Multiple Resolution Bitmap graphics file (Microsoft C/C++)
MRC - mIRC file (mIRC)
MRK - Windows User Benchmark (Win95)
MRS - Macro Resource file (WordPerfect for Win)
MS - Microsoft antivirus report (MSAV)
MSC - Microsoft C makefile ()
MSC - management saved console[1] (Microsoft; Microsoft MMC[2])
MSD - Secure and Encrypted File (mysecuredelivery/Download)
MSDL - Manchester Scene Description Language ()
MSDVD - Windows DVD Maker Project (Windows DVD Maker)
MSE - Set file (Magic Set Editor)
MSG - Message base (e.g. HMB) ()
MSG - Message text file (ASCII) (Microsoft Outlook)
MSG - ZVoice digitized voice file ()
MSI - Windows Installer Package (Windows Operating Systems)
MSO - Microsoft Word OLE Web Page Storage Stream (Microsoft Office)
MSO - Microsoft Outlook metadata for a Microsoft Word 2000 email attachment[3] (Microsoft Outlook)
MSP - Bitmap graphics file (Microsoft Paint)
MSP - Graphics format (Microsoft Paint)
MSPRODUCER - Media Project (Microsoft Producer (for Microsoft PowerPoint XP/2003) Project)
MSQM - data (Microsoft Message Queuing)
MSN - Project (National Instruments for NI MultiSim-Electronic Circuit simulator)
MSS - Manuscript text file (Perfect Writer – Scribble – MINCE – Jove)
MST - Document (MS Test)
MST - Minispecification file (Prosa)
MST - Setup script file (Microsoft Windows SDK)
MSW - Text file (Microsoft Word)
MSX - CP/M archive (MSX)
MTH - Math file (Derive)
MTL - Wavefront ()
MTM - Music format (MultiTracker)
MTS - Master Track Pro Files (MTPro 4)
MTS - data (EA Sports F1 series, car physics)
MTS - MPEG 2 Transport Stream (Various media playback devices / software)
MTV - MTV Ray Tracer graphic file ()
MTW - Datafile (Minitab)
MU - Quattro pro for DOS Menu definition file (Quattro Pro)
MUM - MATLAB CAPE-OPEN Unit Operation Model file (Matlab)
MUM - Microsoft update file (Microsoft)
MUS - Finale music document (Finale)
MUS - Music format (MIDI in Doom) ()
MUS - Sound file (MusicTime)
MUZ - Hover Game MIDI File (Windows' Hover! Game[4])
MVF - Stop frame file (AutoCAD AutoFlix)
MVI - Movie command file (AutoCAD AutoFlix)
MVO - Data (Mad Virgin 3D object)
MVW - Log file (Saber LAN)
MWF - Animation (ProMotion)
MWS - MWave DSP synths instrument (AWAVE)
MXF - Material exchange format (RFC 4539, SMPTE 377M) ()
MXL - PackRat 5.0 support DLLs (PackRat 5.0)
MXM - Material (Maxwell Render)
MXP - Adobe Extension File (Adobe Dreamweaver and Adobe Flash)
MXP - 3ds Max Configuration File (3ds Max)
MXP - MasterCook exported recipe ()
MXT - Data (Microsoft C)
MYD - a MyISAM data file in MySQL (MyISAM, MySQL)
MYP - Presentation (MM Make Your Point)
MZ - Binary-format Map (MazeEdit)
MZE - Text-format Map (MazeEdit)
MZG - Binary-format Map Collection (MazeEdit)
MZX - Binary-format Encrypted Map (MazeEdit)

NAM - Name Space Modules (Novell NetWare)
NAP - Naplps file (VideoShow) (EnerGraphics)
NAPLPS - North American Presentation Layer Protocol Syntax ()
NB - Text file (Nota Bene)
NB - Wolfram Mathematica Notebook (see Wolfram Language) (Mathematica)
NBF - Nokia Backup File (Nokia Mobile Phones)
NBS - Minecraft Note Block Studio file (Minecraft Note Block Studio)
NC - Binary Data (netCDF software package)
NC - Instructions for NC (Numerical Control) machine (CAMS)
NC - Non-error checking preprocessed Goc source code (Geoworks)
NCC - CNC (Computer Numeric Control) control file (CamView 3D)
NCD - NC Drill File (Excellon Format, printed circuit board hole definitions) (Most PCB layout software)
NCD - Norton Change Directory support file (Norton Commander)
NCP - Re-volt Collision file (Re-volt)
ND - NetConnect data file. Contains information on multi-user access to the company file. (Intuit QuickBooks)
NDB - Network database (Intellicom - Compex)
NDS - Nintendo DS ROM file used for Homebrew and commercial (Game) files on DS (Nintendo DS)
NDL - Nodelist file ()
NDX - Index file (dBASE II - III - IV - dBFast)
NEF - Nikon RAW image format (Nikon cameras)
NEIS - Korean Student Record Document (Student Record Writing Program)
NEO - Raster graphics file (Atari Neochrome)
NES - iNES ROM image format ()
NET - Network configuration/info file ()
NEU - Pro/Engineer neutral file format (PTC Pro/Engineer)
netCDF - Network Common Data Format ()
NEW - Ameco Embroidery Format (Embroidermodder)
NEW - New info ()
NFF - Haines Neutral File Format ()
NFF - WorldToolKit Neutral File Format ()
NFO - Folioview database ()
NFO - Help format (Nextpage Folio)
NFO - Info file (Compact NFO Viewer)
NG - Hypertext Database (Norton Guide)
NGC - G-Code file (Inkscape G-Code tools extension)
NGO - NG linker object file (NGML)
NGS - NG compiler source file (NGC)
NIF - netimmerse/gamebyro file ()
NIL - NIL (Icon Hear-It)
NITF - National Imagery Transmission Format ()
NK2 - e-mail address autocomplete archive (Microsoft Office Outlook)
NL - Norton Desktop Icon Library ()
NLM - Netware loadable module (Novell Netware)
NLS - National Language Support file (MS-DOS)
NLX - Form (FormWorx 3.0)
nmf - Node Map File (Used by SpicyNodes)
nnn - Arj archive volumes up to 999 (ARJ)
nnn - Netware unicode rule table (e.g. 1250_Uni.036) (Novell Netware)
nnn - News about smth with ext. of ver. number ()
nnn - RAR archive volumes up to 999 (RAR)
NOT - Notation ()
NOT - Yard Notes File (FYM)
NP - Project schedule (Nokia Planner) (Nokia Planner)
NPI - Source for DGEN.EXE interpreter (dBASE Application Generator)
NPJ - Nile Project (Game Mission Editor)
NPR - Nuendo Project File (Steinberg Nuendo)
NRG - Nero Disc Image File (Nero Express / Burning ROM)
NRW - Nikon Coolpix RAW image (Nikon)
NSA - media (Nullsoft Streaming Audio)
NSF - database (Lotus Notes)
NSF - Music module (NES Sound File)
NSS - Norton screensaver module (NC - NDW Screen Saver)
NST - Music module (Amiga Noise Tracker)
NSV - media (Nullsoft Streaming Video)
NSX - Compound index file (SuccessWare SIX 3.00)
NT - Startup files (Windows NT)
NT3 - BAHN Layout file (JBSS BAHN)
NTF - database design template (Lotus Notes)
NTH - Nokia Theme File (Nokia PC Suite)
NTR - Executable ASCII text file (strip header and rename) (netrun31.zip)
NTS - Executable ASCII text file (strip header and rename) (netsend1.zip)
NTS - Tutorial (Norton)
NTX - Database index file (Clipper 5)
NUF - Message for new users on their 1st call (Procomm Plus)
NUMBERS - Numbers spreadsheet file (Numbers (Apple iWork '08))
NV - NewViews DOS accounting database (QW Page NewViews)
NV2 - NewViews accounting database (QW Page NewViews)
NWS - Info text file (latest news) (ASCII) ()
NXT - Sound (NeXT format) ()

O$$ - Outfile (Sprint)
O - Object file (UNIX - Atari - GCC)
O01 - Typhoon vOice file (AWAVE)
OAZ - Fax (NetFax Manager)
OB - Object cut/paste file (IBM LinkWay)
OBD - Microsoft Office Binder (MSOffice)
OBJ - Compiled machine language code ()
OBJ - Object code (Intel Relocatable Object Module)
OBJ - Wavefront Object ()
OBJF - Data (Triangle strips object)
OBR - Object browser data file (Borland C++)
OBS - Script (ObjectScript)
OBT - Microsoft Office Binder Template (MSOffice)
OBV - Visual interface (ObjectScript)
OBZ - Microsoft Office Binder Wizard (MSOffice)
OCF - Object Craft File (Object Craft)
OCD - OCAD Map File (OCAD)
OCR - Incoming fax transcribed to text (FAXGrapper)
OCT - Musical file (Pctalizer)
OCX - New Custom Control's format in VB 4.0 (Visual Basic)
OCX - OLE custom control ()
ODB - OpenDocument database (OpenOffice.org / LibreOffice Base)
ODF - OpenDocument formula (OpenOffice.org / LibreOffice Math)
ODG - OpenDocument drawing (OpenOffice.org / LibreOffice Draw)
ODIF - Open Document Interchange Format ()
ODL - Object Description Language ()
ODL - Type library source (Visual C++)
ODM - OpenDocument master document (OpenOffice.org / LibreOffice Writer)
ODP - OpenDocument presentation (OpenOffice.org / LibreOffice Impress)
ODS - OpenDocument spreadsheet (OpenOffice.org / LibreOffice Calc)
ODT - OpenDocument text document (OpenOffice.org / LibreOffice Writer)
OEACCOUNT - XML format, account files (Microsoft e-mail software: Outlook Express, Windows Mail, Windows Live Mail, Microsoft Outlook)
OFD - Form definition (ObjectView)
OFF - Object File Format vector graphics file ()
OFF - Object File Format vector graphics ()
OFM - PostScript font description file ()
OFN - Microsoft Office documents (Microsoft Office)
OGG - Ogg multimedia container format ()
OHB - Source (On Hand Basic)
OHS - Outbound History (Bink/+)
OIF - QuickBase file format ()
OKT - Music (8 channels) (Oktalyzer)
OKT - Music format (Oktalyzer)
OLB - Object library (VAX)
OLD - Backup file ()
OLI - Text file (Olivetti)
OLSR - Configuration file (olsrd)
OMA - Audio file (Labelgate CD 2, MAGIQLIP2)
OMG - Audio file (Sony compressed audio file (ATRAC3))
OMF - Open Media Framework (Avid Media Composer)
OOF - Data (Outrage 3D Object Format (Descent))
OOG - Data (WEBOOGL 3D object)
OOM - Swap file (Shroom)
OPJ - Origin Project File (Origin version 4.1 and later)
OPN - Active options (Exact)
OPT - Options (name used by many programs for configuration information)
OPT - Delphi project options (Borland Delphi)
OPT - Optimize support file (QEMM)
OPUS - Ogg/Opus audio file (mpv, mplayer, many others (official file format).)
OPW - Organization chart (Org Plus for Windows)
OPX - Inactive options (Exact)
ORA - Parameter file (Oracle)
ORC - Orchestra MIDI file (CSound)
ORG - Calendar file (Lotus Organizer)
ORG - Older Origin Project (Origin versions 4 or earlier)
OSK - osu! skin (osu!)
OSR - osu! replay (osu!)
OSZ - osu! beatmap (osu!)
OTG - OpenDocument drawing template (OpenOffice.org / LibreOffice Draw)
OTB - Over-the-air bitmap graphics ()
OTF - Subtitle font information for media content (Media players / software which support PGS subtitling)
OTH - OpenDocument HTML document template (OpenOffice.org / LibreOffice)
OTL - Outline font description (Z-Soft Type Foundry)
OTL - Ventura Publisher's Type Foundry Outline Editor format ()
OTL - The Vim Outliner (A vim plugin)
OTP - OpenDocument presentation template (OpenOffice.org / LibreOffice Impress)
OTS - OpenDocument spreadsheet template (OpenOffice.org / LibreOffice Math)
OTT - OpenDocument text document template (OpenOffice.org / LibreOffice Writer)
OTX - Text file (Olivetti Olitext Plus)
OUT - Output file ()
OUT - Design II for Windows Output file ()
OV1 - Overlay file (part of program to be loaded when needed) ()
OV2 - Overlay file (part of program to be loaded when needed) (TomTom Point of Interest)
OVD - Datafile (ObjectVision)
OVL - Overlay file (part of program to be loaded when needed) ()
OVR - Overlay file (part of program to be loaded when needed) ()
OXT - OpenOffice.org extension (OpenOffice.org / LibreOffice)

P - Database PROGRESS source code (PROGRESS)
P - PASCAL source code file ()
P - Parser source code file ()
P - Picture file (APPLAUSE)
P - Rea-C-Time application parameter file (ReaGeniX code generator)
P0? - Split archive UC2 (SAS.EXE)
P10 - Tektronix Plot (GCGW)
P10 - Certificate Request ()
P12 - Personal Information Exchange ("Crypto Shell Extensions")
P16 - Music (16 channels) (ProTracker Studio 16)
P22 - Patch file (Patch22) (Patch22)
P80 - PLM-80 source ()
P86 - PLM-86 source ()
p2v - Backupfile of a project in eventplanning software plan2viz (windowsbased) ()
P3T - PlayStation 3 Theme file (PS3 Theme settings menu)
PA1 - Worktable (PageAhead)
PAC - SBStudio II Package or Song (SBStudio II)
PAC - STAD Image (graphics ?) ()
PACK - ? (?)
PACKAGE - Contents (The Sims 2 - Spore - The Sims 3)
PAD - Automatic print definitions (Produa)
PAD - Keypad definition (Telemate)
PAF - For Personal Ancestral File data files ()
PAGES - Pages document file (Pages (Apple iWork '08))
PAK - Archive (Pak)
PAL - Palette file (Microsoft Draw - Win. Paintbrush - many)
PAL - Palette file (Diablo II)
PAM - PAM Portable Arbitrary Map graphics format (Netpbm)
PAN - Printer-specific file (copy to coreldrw.ink) (CorelDRAW)
PAR - Parameter file (Fractint)
PAR - PARTS application (Digitalk PARTS)
PAR - Permanent output file (Windows 3.x)
PAR - Parity Archive ()
PAR2 - Parity Archive v2 ()
PART - Part of a download file ()
PAS - Pascal language source (Borland Pascal)
PAT - Gravis Ultrasound Patch (Convert (c) Villena)
PAT - Hatch patterns (AutoCAD - Photostyler)
PAT - Vector fill files (CorelDRAW)
PAT - Pattern File (Photoshop)
PAT - GIMP pattern ()
PB - Fax (FAXability Plus)
PB - Phonebook (WinFax Pro)
PB - Proboard Conf. files (Proboard)
PB - Setup file (PixBase)
PB1 - Document (First Publisher for Windows)
PBA - Powerbasic BASIC source code (Genus)
PBD - Phone book (FaxNOW! - Faxit)
PBD - Molecule (protein data bank) ()
PBI - Powerbasic include file (Genus)
PBI - Profiler Binary Input (Microsoft Source Profiler)
PBK - Microsoft Network Phone book (MSN)
PBL - Powerbasic library (Genus)
PBLIB - Power Library (PowerBASIC)
PBM - PBM Portable Bit Map graphics format (Jasc Media C)
PBM - Planar bitmap graphics (XLib)
PBO - Profiler Binary Output (Microsoft Source Profiler)
PBT - Profiler Binary Table (Microsoft Source Profiler)
PC - Text file containing IBM PC specific info ()
PC3 - Custom palette (Harvard Graphics 3.0)
PC8 - ASCII text IBM8 character set (NewWave Write)
PCA - Perfect Clarity Audio (Sony Vegas Pro)
PCB - P-CAD database (P-CAD, PCBExpress, and other Printed Curcuit Board design software)
PCB - Artwork design file (Circuit board design) (Zuken CadStar)
PCC - Cutout picture vector graphics (PC Paintbrush)
PCD - Graphics format (Kodak Photo-CD) ()
PCD - Kodak Photo-CD Image graphics file (768x512) (hpcdtoppm)
PCD - Pfaff Embroidery Format (Embroidermodder)
PCF - Pixel Coordination Format ()
PCH - Patch file ()
PCH - Precompiled header (Microsoft C/C++)
PCJ - Multimedia authoring tool graphics file (IBM's Linkaway-Live)
PCK - Pickfile (Turbo Pascal)
PCL - HP-PCL graphics data file (HP Printer Command Language)
PCM - OKI MSM6376 synth chip PCM (AWAVE)
PCM - PCM (Authorware)
PCM - Pfaff Embroidery Format (Embroidermodder)
PCQ - Pfaff Embroidery Format (Embroidermodder)
PCS - Microsoft PowerPoint picture package (Microsoft PowerPoint - Microsoft ClipArt Gallery)
PCS - PCSurvey file (PCSurvey by Softart - Land Surveying Software)
PCS - Pfaff Embroidery Format (Embroidermodder)
PCT - Bitmap graphics file (Macintosh b&w PICT1 - color PICT2)
PCW - Text file (PC Write)
PCX - PC paintbrush bitmap format (QPeg - Display - ZSoft - PC Paintbrush, XnView)
PDA - Bitmap graphics ()
PDB - Packrat 5.0 data file (Packrat 5.0)
PDB - container format (envelope) for Palm OS databases (Palm OS, Garnet OS, Access Linux Platform, e-book)
PDB - debugging data (Microsoft Windows)
PDB - Molecule (protein data bank) ()
PDD - Adobe Photoshop Elements Image (Adobe Photoshop Elements)
PDE - Pathology Data Exchange ()
PDE - data (PowerDesk Encrypted)
PDF - Adobe's Portable Document Format (Adobe Acrobat Reader)
PDF - Graphics file (ED-SCAN 24bit format) ()
PDF - Package Definition File ()
PDF - PCAD Database Interchange Format (Pdifin.exe - Pdifout.exe)
PDF - Print device information Netware ()
PDG - Print Shop Deluxe data file ()
PDI - Portable Database Image ()
PDL - Project Description Language file (Borland C++ 4.5)
PDM - Program (Deskmate)
PDM - PowerDesigner's physical data model (relational model) file format (PowerDesigner)
PDM - Visual Basic (VB) Project Information File (Visual Basic)
PDN - Image file (Paint.NET)
PDS - PALASM Design Description ()
PDS - Pds graphics ()
PDS - Planetary Data System Format ()
PDS - Pldasm source code file (hardware assembly) ()
PDV - Printer driver (Paintbrush)
PDW - Document (Professional Draw)
PEB - Program Editor bottom overflow file (WordPerfect Library)
PED - Program Editor delete save (WordPerfect Library)
PEM - Program Editor macro (WordPerfect Library)
PEQ - Program Editor print queue file (WordPerfect Library)
PER - Program Editor resident area (WordPerfect Library)
PES - Program Editor work space file (WordPerfect Library)
PET - Program Editor top overflow file (WordPerfect Library)
pet - package[5] (Puppy Linux)
PEX - Proboard EXecutable file (Executed from PB) (Proboard)
PFA - PostScript Font File ()
PFA - Type 3 font file (unhinted PostScript font) ()
PFB - Adobe Acrobat document (Adobe Acrobat Reader)
PFB - PostScript font (Adobe Type Manager (ATM))
PFC - (Personal Filing Cabinet) contains e-mail, preferences and other personal information (AOL)
PFC - Text file (First Choice)
PFK - Programmable function keys (XTreePro)
PFM - PostScript Type 1 font metric file (Microsoft Windows, Adobe Acrobat Reader)
PFM - Windows Type 1 font metric file ()
PFS - Database (PFS:FILE) - text file (PFS:Write) (PFS)
PFT - Printer font (ChiWriter)
PG - Page cut/paste file (IBM LinkWay)
PGD - PGP cripted disk ()
PGI - Printer Graphics File device driver (PGRAPH library)
PGL - HP Plotter vector graphics format ()
PGM - Graphics format (Portable GrayMap) (JASC Media C)
PGM - Program (Signature)
PGP - Support file (Pretty Good Privacy RSA System)
PGS - Manual page (man4dos)
PH - Optimized .goh file (Geoworks)
PH - Perl header file ()
PH - Phrase-table (Microsoft C/C++)
PHD - PolyHedra Database ()
PHM - Phone book (DN - Lync)
PHN - Phone list (UltraFax - QmodemPro)
PHO - Phone database (Metz Phone for Windows)
PHP - PHP file ()
PHP3 - PHP 3 file ()
PHP4 - PHP 4 file ()
PHF - Database File (Nuverb Systems Inc: Donarius)
PHR - Phrases (LocoScript)
PI2 - Portrait Innovations High Resolution Encrypted Image file (Portrait Innovations Studio2 (proprietary))
PIC - 123 Vector graphics format (CShow - Alchemy - Paint (Pictor))
PIC - Bitmap graphics file (Macintosh b&w PICT1 - color PICT2)
PIC - Lotus picture ()
PIC - PIXAR picture file (SDSC Image Tool)
PICT - Macintosh Picture ()
PIE - GlovePIE script file (GlovePIE)
PIF - OS/2 graphics metafile (PICVIEW.EXE)
PIF - Program Information File (Windows 3.x, 9x, NT)
PIF - Vector graphics GDF format file (IBM mainframe computers) ()
PiM - Pascal Text Mode Image File (The Ultimate Draw)
PIPE - PIPE-FLO project design file (PIPE-FLO Professional)
PIT - Compressed Mac file archive created by PACKIT (unpackit.zoo)
PIT - Partition Information Table for Samsung's smartphone with Android (Odin3)
PIT - File used to connect to a remote system. (Dell (previously Quest) vWorkspace)
PIV - Pivot Stick Animator file (Pivot Stick Animator)
PIX - Alias image file (SDSC Image Tool)
PIX - Inset Pix ()
PJ - Project (CA-SuperProject)
PJT - Additional (FPT) project description file (FoxPro)
PJX - Main (DBF) project description file (FoxPro)
PK - PacKed bitmap font bitmap file (TeX DVI drivers) ()
PK - Peak file (Cool Edit)
PKL - Pickle file (Python object serialization)
PK2 - Quake 2 data file (id Software)
PK3 - Quake 3 data file (id Software)
PK4 - Doom 3 and Quake 4 data file (id Software)
PKA - Archive (PKARC)
PKG - Installer script (Next, Mac OS X, Sony PS3)
PKG - P-CAD database (P-CAD)
PKT - Fido message packet (FTN software)
PL - Palette (Harvard Graphics)
PL - Perl source code file ()
PL - Prolog source code file ()
PL - Property List font metric file (TeX)
PL1 - Room plan (3D Home Architect)
PL1 - PL/I source file (PL/I compilers)
PL2 - Palette (Diablo II)
PL3 - Chart palette (Harvard Graphics 3.0)
PLA - Playlist ()
PLANTUML - UML Diagram (also PU) (PlantUML)
PLB - FoxPro library (FoxPro)
PLB - P-CAD library (P-CAD)
PLC - Add-in file (functions - macros - applications) (Lotus 1-2-3)
PLC - P-CAD database (P-CAD)
PLD - PhotoLine Document (PhotoLine image processing)
PLE - Encrypted Chat Log (Messenger Plus! Live Plugin - Log viewer)
PLI - PL/I source file (PL/I compilers)
PLIST - Mac OS Property List, also used on iOS, NeXTSTEP, and GNUstep (Apple's Property List Editor)
PLL - Prelinked library (CA Clipper)
PLM - DisorderTracker2 music module (AWAVE)
PLN - Spreadsheet (WordPerfect for Win)
PLP - Playlist ()
PLP - Messenger Plus! Sound Pack (Messenger Plus! Live Plugin)
PLS - Playlist file (WarpVision (OS/2))
PLSC - Messenger Plus! Script Pack (Messenger Plus! Live Plugin)
PLSK - Messenger Plus! Skin Pack (Messenger Plus! Live Plugin)
PLT - HPGL plotter file vector graphics (AutoCAD)
PLT - Output file for ploter ()
PLT - P CAD: Output file editor for PCPLOT or PCPRINT (P CAD)
PLT - Page Magic 2.0 paper format (Page Magic 2.0)
PLT - Palette ()
PLT - Table for .pll (CA Clipper)
PLY - Data (PopMail)
PLY - Presentation screen (Harvard Spotlight)
PLY - ZipPack ()
PLY - Polygon File Format or the Stanford Triangle Format. (3D Scanners)
PLY2 - Data (PLY2 object)
PM - Auran Jet progressive mesh file (obsoleted by IM and LM) (Trainz)
PM - Perl module ()
PM - Bitmap graphics (Presentation Manager)
PM3 - PageMaker 3.0 data file (PageMaker 3.0)
PM4 - Document (PageMaker 4)
PM5 - Aldus PageMaker 5.0 publication (Aldus PageMaker)
PMA - PMarc Archive ()
PMC - Graphics (A4TECH Scanner)
PMI - OS/2 V3 SVGA PMI-File (Svga.exe)
PMI - PhatPad note (PathWare)
PMM - Program file (Amaris BTX/2)
PMP - PhotoMorph Project (PhotoMorph)
PN3 - Printer device driver (Harvard Graphics 3.0)
PNG - Portable Network Graphics ()
PNCL - Pinnacle file - Pinnacle by Optys Tech Corporation (Pinnacle file)
PNF - Pre-compiled Setup Information file (Microsoft Windows)
PNM - PBM Portable aNy Map graphics file ()
PNT - Macintosh painting ()
PNT - Pointlist segment (FTN software)
PNT - QWK reader pointer file (MarkMail 2.x)
POD - UNIX perldoc File ("Plain Old Documentation") (pod2man, pod2html)
POF - Altera FPGA programming file (External Flash) (Altera Quartus)
POH - Optimized .goh file (Geoworks)
POL - InnovMetric Software Polygon Models Format ()
POLICY - Group Policy File (Microsoft Windows)
POLY - Data (Patrick Flynn's Poly Format - 3D object)
POP - Messages index (PopMail)
POP - Pop-up menu object (dBASE Application Generator)
POT - Microsoft PowerPoint template ()
POV - Raytraced graphics image (Persistence Of Vision)
POW - Power Chords instrument/song file (Power Chords)
PP - Amiga archive (POWERPACKER)
PPA - Microsoft PowerPoint Add-in ()
PPB - Button bar for Print Preview (WordPerfect for Win)
PPD - PostScript printer description file ()
PPJ - Premiere Project (Premiere)
PPK - Archive (using for many distributives) (PPK)
PPL - PolaroidPalettePlus ColorKey device driver (Harvard Graphics 3.0)
PPM - Graphics format (Portable PixelMap) (JASC Media C.)
PPO - Preprocessor output (CA Clipper 5.*)
PPP - Publication (PagePlus)
PPS - Storyboard (Personal Producer)
PPS - Microsoft PowerPoint Slideshow (stand alone slideshow) ()
PPT - Microsoft PowerPoint Presentation (Microsoft PowerPoint)
PPTX - MS Office Open-XML Presentation (Microsoft PowerPoint)
PPSX - MS Office Open-XML Auto-Play Presentation (Microsoft PowerPoint)
PR1 - Packrat 4.0 data file (Packrat 4.0)
PR2 - Packrat 4.x data file (Packrat 4.x)
PR2 - Presentation (Aldus Persuasion 2.x)
PR2 - Printer driver (dBASE IV)
PR3 - PostScript printer driver (dBASE IV)
PR3 - Presentation (Aldus Persuasion 3.x)
PRC - container format (envelope) for Palm OS databases (Palm OS, Garnet OS, Access Linux Platform, Mobipocket)
PRC - "Product Representation Compact", for embedding 3D data in a PDF file (CAE and CAM applications)
PRD - Printer driver ()
PRE - Presentation (Freelance Graphics)
PRE - Settings (Programmer's WorkBench, Microsoft C/C++)
PRE - Stork graphic file ()
PRF - CheckIt Pro v1.0 data file (CheckIt Pro 1.0)
PRF - Pixel Run Format graphics file (Improces - Fastgraph)
PRF - Printer driver (dBASE IV)
PRF - Profiler output ()
PRG - Program source code (e.g. Clipper language) (CA Clipper)
PRG - Program source (dBASE IV - FoxPro - Clipper 5 - dBFast)
PRG - Program (Atari)
PRI - Printer definitions (LocoScript)
PRJ - Borland C++ IDE project file (BC.EXE - BCW.EXE)
PRJ - Mkd (Unix command) (Mkd project file to extract documentation)
PRK - SimPark Saved File (SimPark)
PRM - Parameters ()
PRN - Printer driver (Signature)
PRN - Text file (Lotus 1-2-3 - Symphony)
PRN - Usually printer output file ()
PRO - Profile (used by many programs to store configuration data)
PRO - Graphics profile file (DOS)
PRO - Proboard conf. file (Proboard)
PRO - Punch! Home Design File (Punch! Home and Landscape)
PRO - Prolog language source ()
PRO - PROLOG source code file ()
PROJ - Project File (Interface Builder) (NeXT)
PROPERTIES - Java properties file (Java applications)
PROTO - Message specification (Google Protocol Buffers)
PRR - The Perfect Resume data file (Perfect Resume)
PRS - Norton Viewer DLL file ()
PRS - Presentation (Harvard Graphics Win)
PRS - Printer Resource e.g. fonts (WordPerfect for Win)
PRS - Procedure (dBASE IV)
PRT - P-CAD component (P-CAD)
PRT - Part or Drawing (Cadkey)
PRT - Printer driver (Dr. Halo)
PRX - Compiled program (FoxPro)
PS - Document in PostScript format (adobe)
PSA - Archive (Pretty Simple Archive) (PSA.OUT (GNU))
PSB - For big Photoshop files (Photoshop Document)
PSD - Design II for Windows Process Simulation Diagram ()
PSD - Periscope Debbuger Def file (Periscope)
PSD - Photoshop bitmap file (Photoshop document)
PSE - see PSEG ()
PSEG - Bitmap graphics (IBM printer Page SEgment)
PSF - Outline PostScript printer font (ChiWriter)
PSM - Music format (Protracker Studio Module) (Protracker - MASI)
PSM - Symbol table of IDE (Turbo Pascal)
PSM - 3D Model (18 Wheels Of Steel)
PSN - Presentation file for Sound Script (Win)
PSP - image file with layers (Paint Shop Pro (all versions))
PSQ - Premiere Sequence (Premiere)
PST - Postbox file (BMail)
PST - Archive File (Microsoft Outlook)
PSV - PlayStation 2/PlayStation 3 saved game (PlayStation 2 and PlayStation 3)
PSW - File w/ passwords for any program/game (many)
PT - Game crack (Player Tools)
PT - Kodak Precition Color Management System ()
PT3 - Device driver (Harvard Graphics 3.0)
PT3 - Template (PageMaker 3)
PT4 - Template (PageMaker 4)
PT5 - Aldus PageMaker 5.0 publication template (Aldus PageMaker)
PTB - Power Tab Software (Power Tab Editor)
PTB - Script (PubTech BatchWorks)
PTF - PlayStation Portable Theme file (PSP Theme settings menu)
PTF - Pro Tools Session File (Digidesign Pro Tools)
PTG - Panasonic Title Graphics ()
PTL - Premiere Title (Premiere)
PTM - Macro (PubTech BatchWorks)
PTM - Music format ()
PTM - Page Magic 2.0 template (Page Magic 2.0)
PTN - Pattern (Cadkey)
PTN - Pattern (CarveWright/CompuCarve Designer)
PTR - OS/2 cursor image file (ICONEDIT.EXE)
PTR - QWK reader pointer file (QMail)
PTU - Performer Terrain Utilities ()
PTX - Pro Tools 10 session file (Avid Pro Tools)
PU - UML Diagram (also PLANTUML) (PlantUML)
PUB - Package File (Exstream Dialogue)
PUB - Page template (Microsoft Publisher)
PUB - Public key ring file (Pretty Good Privacy RSA System)
PUB - Publication (Ventura Publisher - 1st Publisher)
PUD - Warcraft II Map file (Warcraft II)
PUT - Archive (PUT)
PUT - Graphics format (WScan)
PVD - Script (Instalit)
PVK - Private Key File (Microsoft Authenticode)
PVL - Library (Instalit)
PVM - Texture Files (PVMEdit)
PVT - Local Fidonet pointlist (FTN software)
PW - Text file (Professional Write)
PWF - Workflow Files (Mac OS X Server Podcast Producer)
PWK - Workspace File (PolyWorks)
PWL - Password List ()
PWP - Text document (Professional WritePlus)
PX - Paradox 3.0 file (Paradox 3.0)
PXP - 3DS Process file (3D Studio)
PXR - Pixiar Picio (AltamiraComposer)
PXZ - Compressed file to exchange media elements (PSALMO)
PY - Python script file (Python interpreter)
PYC - Compiled Python module (Python interpreter)
PYD - Python DLL (Python interpreter)
PYI - Cognos Powerplay Model ()
PYK - PYK Compressed File (PYK)
PYO - Optimized compiled Python module (Python interpreter)
PYW - Python Script Without Console Window (Python interpreter)
PZD - Default settings (Pizazz Plus)
PZI - Graphics format (PZP)
PZO - Overlay file (Pizazz Plus)
PZP - Palette (Pizazz Plus)
PZS - Settings (Pizazz Plus)
PZT - Transfer file (Pizazz Plus)
PZX - Swap file (Pizazz Plus)

Q0 - Q0 graphic file ()
Q3S - Data (Quick3D Scene)
QAG - Quick Access Group (Norton Desktop)
QAP - Application (Omnis Quartz - Omnis Studio)
QB - Tony Hawk's Pro Skater series scripting files ()
QBB - Quickbooks Backup File ()
QBE - Saved query (Query By Example) (dBASE IV - Quattro Pro)
QBO - Compiled query (dBASE IV)
QBW - Spreadsheet (QuickBooks for Windows)
QCH - Qt Compressed Help (Trolltech Qt Assistant)
QCP - Mp3 extension on Motorola ringtones (Motorola Phones)
QDF - Data file (Quicken data file)
QDK - Backup of startup files created by Optimize (QEMM)
QDn - Data file - segment n (Omnis Quartz- Omnis Studio)
QDV - Graphics file (Steve Blackstock Giffer)
QDR - Configuration file (Q-Dir)
QEF - Query file (Q+E for Microsoft Excel)
QFX - Quicken-specific implementation of the OFX specification (Intuit Quicken)
QFX - Fax (QuickLink)
QG3 - Data (QuickMem Greek)
QHC - Qt Help Collection (Trolltech Qt Assistant)
QHCP - Qt Help Collection Project (Trolltech Qt Assistant)
QHP - Qt Help Project (Trolltech Qt Assistant)
QIF - Quicken Interchange Format (Intuit Quicken)
QIZ - World book quiz (World Book)
QLB - Quick library (Microsoft C/C++)
QLC - ATM Type 1 fonts script (Adobe Type Manager)
QLP - Printer driver (QuickLink)
QM4 - Options or services file (QMail 4.x Mail Door)
QPR - Generated query program (FoxPro)
QPR - Print queue device driver (OS/2)
QPX - Compiled executable QBE query file (FoxPro)
QRP - Database report file (QuickReport)
QRS - Equation Editor support file (WordPerfect for Win)
QRT - Graphics format (QRT ray tracing) ()
QRY - Query (dBASE IV)
QT - QuickTime movie (animation) ()
QTVR - QuickTime VR Movie ()
QUOX - Question Object Document (Quobject Designer and Quobject Explorer)
QVD - QlikView Document (Data) (QlikView Compressed Database File)
QVW - QlikView Document (View) (QlikView Presentation File)
QWK - QWK reader message file ()
QXD - Document (QuarkXPress)
QXL - Element library (QuarkXPress)

R - Ratfor file ()
R - Script file (R)
R00, R01, ... - Part of a multi-file RAR archive ()
R2D - Reflex 2 datafile (Reflex 2)
R3D - Red Raw Video (raw video data created with a Red camera) (Red Camera)
R8 - Raw graphics file (one byte per pixel) plane one (PicLab)
R8P - PCL 4 bitmap font file (Intellifont)
RA - Remote Access conf. files (RA)
RA0, RA1, ... - Part of a multi-file RAR archive ()
RAD - 2-op FM music (Reality AdLib Tracker)
RAD - Radiance ()
RAL - Remote Access Language file (Remote Access)
RAM - Ramfile (RealAudio)
RAR - Archive (RAR)
RAS - Graphics format (SUN Raster)
RAT - Datafile (RATS) ()
RAW - HSI raw graphic file ()
RAW - PCM Signed Raw Sound File ()
RAW - QRT graphic file ()
RAY - Rayshade ()
RB - Ruby Script file ()
RBF - Datafile (Rbase)
RBXM - ROBLOX "model" (ROBLOX)
RBXL - ROBLOX "level" (ROBLOX)
RC - Configuration file (emacs)
RC - Resource Compiler script file (Microsoft C/C++, Borland C++)
RC - Resource Script (Resource Writer)
RC - UUPC configuration files (UUPC)
RC - Windows resource compiler script (RC.EXE -Resource WorkShop - OS/2)
RCG - Netscape newsgroup file (netsc.rcg) ()
RCT - Roller Coaster Tycoon ()
RData - Data file (R)
RDF - Compiled UIC source code (Geoworks UI Compiler)
RDI - Device-independent bitmap file (RIFF RDIB format) ()
RDP - RDP connection (Remote Desktop connection)
RDX - Datafile (Reflex)
REC - Archivation protocol (ARCSERVE)
REC - Datafile (EpiInfo)
REC - Record file (Sprint)
REC - Windows Recorder Macro File (WinRecorder)
RED - Path info (Clarion Modula-2)
RED - REDuced nodelist file (T-Mail nodelist Compiler)
REF - Cross-reference ()
REG - OLE Registration file (Windows 3.x)
REG - Registration information or key ()
REL - Foreground job relocatable file (RT-11)
REM - Remarks definition (Sourcer)
REM - Remarks ()
REP - QWK reader reply file ()
REP - Report file used by many applications ()
REP - Report (Report Designer - CodeReporter - DataBoss)
REQ - File request (FTN Software)
RES - Compiled resource (Microsoft C/C++, Borland C++)
RES - DBASE resources (dBASE IV)
RES - Windows compiled resource package (Win)
REV - Revision file (Geoworks)
REX - PharLab executable file (old format) (PharLab)
REX - Report definition (Oracle)
REX - Rexx language source file (Rexx)
REZ - Resource file ()
RF - Sun raster graphics file ()
RFM - Report ForMat (script for customized report) (Nuverb Systems Inc: Donarius)
RFT - DCA/RFT Revisable Format Text file (IBM DisplayWrite 4.0-5.1)
RGB - SGI RGB image file (RAW) (SDSC Image Tool)
RGX - Symbol tables etc. info (ReaGeniX code generator)
RH - Resource header file (Borland C++ 4.5)
RH - Windows resource file header (RC.EXE)
RHistory - Command history logfile (R)
RI - Data (Lotus 1-2-3)
RIB - Graphics (Renderman Interface Bytestream) (3D Reality)
RIC - Fax (Ricoh)
RIF - RIFF bitmap graphics (Resource Interchange File Format) (Fractal Design Painter)
RIP - TeleGrafix Remote Imaging Protocol (Maximus 3.0)
RIX - Graphics (ColoRIX Image File) (ColoRIX)
RL4 - Bitmap graphics ()
RL8 - Bitmap graphics ()
RLA - Wavefront raster image file (SDSC Image Tool)
RLB - Data hgw.rlb (Harvard Graphics Win)
RLC - Graphics 1bit/pixel scanner output ()
RLD - Norton Commander 5.0 temp file (NC 5.0)
RLD - OSIMapDef. RecLoad Definition ()
RLE - Utah Run Length Encoded rasterfile graphic file (SDSC Image Tool)
RLZ - REALIZER source code file (CA-Realizer)
RM - RealMedia (RealPlayer)
RMB - data (RegistryMaster)
RMI - Windows alternate synthesized sound format (RIFF RMID format)
RMK - Make file (CA Clipper - RMAKE)
RMVB - RealMedia Variable Bitrate (RealPlayer)
RN - XPL program for Nota Bene users ()
RNA - Real Native Application File ()
RND - Rendering Slide (AutoCAD AutoShade)
Rnn - Multi volume RAR archive (RAR)
RNO - Runoff file (VAX)
ROL - FM music Adlib Music File (Roland)
ROM - Read Only Memory image in emulators, AONs, etc. ()
ROO - CODASYL DBMS Database Root (Oracle)
RPB - Data report file used by CP Backup (CP Backup)
RPC - Rich Photorealistic Content (ArchVision)
RPD - Database (RapidFile)
RPF - AutoCAD pattern (ACAD)
RPL - Text document (Replica)
RPM - Red Hat Package Manager (Red Hat Linux)
RPT - Report file used by many applications ()
RRD - Reduced Resolution Dataset (ESRI (GIS))
RS - Data file (Amiga Resource - Reassembler)
RS - Rust language source ()
RS_ - Resource fork of a Macintosh file (Mac-ette)
RSC - Resource file (ViewMax - many)
RSL - Application - Project (resolver one)
RSL - Resource Library used by PC Tools for Windows (PC Tools - Win)
RSP - Response file (text file containing input expected by e.g. LINK) ()
RSP - Response File (OS/2)
RST - reStructuredText (Docutils)
RSY - FLEXIT Multishot Survey Raw Data file (FLEXIT)
RTF - Rich Text Format text file (help file script) (many - Microsoft Word)
RTFD - RTF-Packet (NeXT)
RTL - HP RTL graphic file ()
RTL - Run-Time library (Norton Utilities)
RTL - Text file ()
RTP - RTPatch software update package data file (Pocket soft patch)
RTS - Realizer executable file ()
RTS - Runtime library file (CA-Realizer)
RUL - Echo-conference rules ()
RUN - AMPL script file (AMPL)
RUN - PC Tools for Windows batch file (PC Tools)
RUNZ - pseudo-executable file, used in Portable Apps and software installers for Super OS (RUNZ Framework)
RUS - Russian text ()
RV - Mobile pricelist data file (Mobile)
RVF - TRichView ()
RVW - Review ()
RV - Raw Wind Data ()
RWS - Borland Resource Workshop symbol file (Resource Workshop)
RWS - Resource Workshop data file (Borland C++)
RWX - Criterion RenderWare ()
RWX - MEME Shape File ()
RWX - Script (RenderWare)
RWZ - Microsoft Outlook Rules Wizard File (Microsoft Outlook)
RXD - Reflex 1 datafile (Reflex 1)
RZK - File Crypt password file (All text editors)
RZX - File Crypt encrypted file (File Crypt (Akte Krypta, Kriptirnik))

S$$ - Temporary sort file (Sprint)
S - ASSEMBLY source code file (unix)
S - Multi Edit macro file source (Multi Edit)
S - MSTS Shape file (MSTS)
S19 - Motorola ASCII format of executables ()
S1K - S1000 Simnet Format ()
S3I - Digiplayer/ST3 Sample File (Digiplayer - ST3)
S3M - Music (16 channels) (Scream Tracker 3.0 - DMP)
S7I - Seed7 library / include file (Seed7 interpreter and compiler)
SA? - Packed mail (FTN software)
SAB - Saber file (Star Wars: Jedi Knight Jedi Academy)
SAF - see SAIF ()
SAFE - SafeIT Encrypted ()
SAIF - Spatial Archive Interchange Format ()
SAL - Datafile (SORITEC)
SAN - LucasArts' SMUSH/INSANE animation ()
SAM - Ami Pro data file (Ami Pro)
SAM - Text file (Samna - Lotus Ami/Ami Pro)
SAP - Atari SAP music format ()
SAR - Archive (SAR)
SAT - ACIS ACIS .sat ()
SATS - Static source (ATS)
SAV - Backup file (saved file) ()
SAV - Configuration ()
SAV - Executable (RT-11)
SAV - SPSS "System File" (PSPP)
SAV - Saved game state (Spider Solitaire (Windows))
SAVER - Screensaver (Mac OS X)
SB - Audio file (signed byte) ()
SB - Raw Signed Byte (8bit) data (AWAVE)
SB - Raw Signed PCM Byte 8bit data (AWAVE)
SB - Scratch project (Scratch)
SB2 - Scratch 2.0 project (Scratch)
SBD - Storyboard (Storyboard Editor)
SBH - Header (ScriptBasic)
SBI - Sound Blaster Instrument file (Creative Labs) ()
SBK - Emu SoundFont Bank (AWE32 Bank) (Convert (c) Villena)
SBL - Stony Brook Pascal library (SB Pascal)
SBP - DML program (Superbase 4)
SBR - Support file (Source Browser)
SBT - Notes related to record (Suberbase 4 Windows)
SC - Display driver (Framework II)
SC - PAL script (Paradox)
SC - Script (Borland Paradox)
SC3 - Renamed dBASE III screen mask file (dBASE IV)
SC3 - Screen device driver (Harvard Graphics 3.0)
SC3 - Saved City (SimCity 3000)
SC4 - Saved City (SimCity 4)
SC4 - Game Scenario (RollerCoaster Tycoon Deluxe/Expansion Pack)
SC6 - Game Scenario (RollerCoaster Tycoon 2)
SCA - Datafile (SCA)
SCC - Text file ()
SCD - SCODOL film recorder (Scan Conversion Object Description Language) (SCODOL)
SCF - Standard Chromatogram Format (DNA Baser Assembler)
SCF - Standard Chromatogram Format (Staden package)
SCF - ? (SimAnt or SimTown ??)
SCF - Windows Explorer Command (e.g.: show desktop.scf) (Windows Explorer)
SCF - Multimedia show (ScoreMaker)
SCF - Spelling checker configuration file (Symphony)
SCH - Project schedule (Schedule Publisher)
SCH - Circuit Design Schematic (P-CAD - Orcad - Protel)
SchDoc - Circuit Design Schematic (Protel - Altium Designer)
SCHEMATIC - MCEdit Schematic file (MCEdit Tool for Minecraft)
SCI - Fax (SciFax)
SCI - System Configuration Information ()
SCM - Scheme source code file ()
SCM - Schematic file (Circuit Diagram for PCB design) (Zuken CadStar)
SCM - StarCraft mission ()
SCN - SCeNe RTrace ()
SCN - Screen file (Kermit)
SCO - High score ()
SCP - Script (BITCOM)
SCR - Any other screen system ()
SCR - DEBUG source code file (DOS Debug)
SCR - Forth screen (source) file (Forth)
SCR - Screen - screen snapshot (dBASE IV - Procomm Plus)
SCR - Screen font (LocoScript)
SCR - Screen saver (Windows 3.x)
SCR - Screen snapshop ()
SCR - Script file source (TeleMate - Kermit - 1st Reader)
SCT - Additional (FPT) screen description file (FoxPro)
SCTOR - Raster graphics format used by some very obscure custom operating systems ()
SCX - Chart (Stanford Chart)
SCX - Graphics format (ColoRIX)
SCX - Main (DBF) screen description file (FoxPro)
SCX - StarCraft: Brood War scenario (StarCraft: Brood War)
SCY - Security file (ReaGeniX)
SD - Sound Designer I audio file (AWAVE)
SD7 - Seed7 source file (Seed7 interpreter and compiler)
SDA - Fidonet's Software Distribution Network file archive description ()
SDC - Video (DigimaxMaster - Samsung NV3)
SDC - Synopsys Design Constraints (Electronic Design Automation Tools)
SDF - Microsoft SQL Server Compact Edition database file ()
SDF - Flight data (microdrones GmbH)
SDF - Source definition file (Sourcer)
SDF - System Data Format file (fixed length ASCII text) ()
SDI - Software Distribution Network Info file ()
SDK - Roland S-550/S-50/W-30 Disk Image ()
SDL - Alias Wavefront Scene Description Language ()
SDM - Signed Differential Mapping brain maps and/or distributions (Signed Differential Mapping)
SDML - Spatial Data Modeling Language ()
SDN - Software Distribution Network compressed file archive (pak251.exe)
SDR - SmartDraw File (SmartDraw Pro)
SDS - MIDI Sample DUMP Standard File ()
SDS - Self Defining Structure provides for N-dimensional very large datasets using HHCode (geographic information systems and relational database management systems)
SDTS - Spatial Data Transfer Standard ()
SDW - Ami Draw Symbol File ()
SDX - Sample DUMP Exchange File ()
SEA - Self-Extracting compressed Macintosh file Archive ()
SEC - compressed file ()
SEC - Diskreet encrypted file (Diskreet)
SEC - Secret key ring file (Pretty Good Privacy RSA System)
SEC - Secured animation file (Disney Animation Studio)
SED - Self extraction directive file (IExpress)
SEN - Scifer Archive Format (Internal Header Mode) ()
SEP - Printer separator page ()
SEQ - ABI Text Sequence (Applied Biosystems)
SEQ - Atari animation file ()
SEQ - Video (Tiertex video sequence)
SEQ - Sequential Instruction File (Bubble Chamber)
SES - Session info (Clarion Modula-2)
SES - Multitrack Audio Session info (Adobe Audition)
SET - Configuration file (1st Reader)
SET - Driver sets created by Install (Symphony)
SET - Extension used by Norton Backup and CPS Backup for setup info (Norton Backup - CPS Backup)
SET - Hump Assignments File (FYM)
SET - Setup options file ()
SET - YVD card set file (YVD)
SF - IRCAM Sound File (CSound package - MixView sound sample editor)
SF - JAR Digital Signature ()
SF - WPS attribute storage (OS/2 WorkPlace Shell) wp_root.sf (OS/2 WorkPlace Shell)
SF2 - Emu SoundFont Bank v2.0 file (AWAVE)
SFB - Configuration file (emacs)
SFB - HP Soft font (obsolete under Windows) ()
SFD - SoundStage Data file (AWAVE)
SFF - Standard Flowgram Format (DNA Baser SFF Workbench tool)
SFF - Scene File Format ()
SFI - Graphics (SIS Framegrabber)
SFI - Printer font (HP LaserJet landscape) (Ventura Publisher)
SFL - PCL 4 bitmap font (landscape) (landscape - Intellifont - Ventura Publisher)
SFL - Sound file (Sound Forge and ACID Pro)
SFN - Font (SPX)
SFO - Bitstream font file - fontware format ()
SFP - PCL 4 bitmap font (portrait - Intellifont - Ventura Publisher)
SFR - Sonic Foundry Sample Resource (AWAVE)
SFS - PCL 5 scalable font file (Intellifont)
SFT - Screen font (ChiWriter)
SFV - Simple file verification checksum file (many file verification tools)
SFX - Renamed dBASE III screen mask file (dBASE IV)
SFX - SFX (self-extracting archives) script (RAR)
SG1 - Graphics (Stanford Graphics)
SGF - Document with graphics (Starwriter)
SGF - Smart Game Format (Many board games)
SGI - Graphics file (IRIS - Silicon Graphics)
SGP - Statistics (STATGRAPHICS Plus)
SGT - Save/get keyboard macro (Signature)
SH - ASCII archive (SHAR)
SH - Unix shell script (Unix shell interpreter)
SH3 - Presentation (Harvard Graphics 3.0)
SH3D - Sweet home 3d file (Sweet home 3d)
SHA1 - SHA1 Checksum verification File (HashCheck (Windows))
SHAR - Archive (UNSHAR (Unix))
SHB - Background (CorelShow)
SHG - Segmented Hyper Graphics (Microsoft's shed.exe, JGsoft's Hotspot Builder, EC Software's Help and Manual)
SHK - Apple II archive (SHRINKIT)
SHM - Shell macro (WordPerfect Library)
SHP - Shape file and source file for text fonts (AutoCAD)
SHP - ESRI shapefile (ArcGIS)
SHR - see SHAR ()
SHT - HTML format for WWW (NetScape)
SHW - Presentation (Harvard Graphics 2.0 - CorelShow)
SHW - Slide show (WordPerfect Presentations, PMview Slide Show)
SHX - Shape entities (AutoCAD)
SHX - ESRI shapefile (ArcGIS)
SIB - Sibelius file (Sibelius 1-5)
SID - Sound Interface Device file format (SIDplayer, SIDplay, sidplay2 /w)
SIF - Setup Installation Files info (Windows NT Setup)
SIG - Current program settings (Signature)
SIG - Signature file (ThunderByte AntiVirus - PopMail)
SIK - Backup file (Sicherungskopie) (Microsoft Word)
SIM - Simon document file - Simon instruction software editor ()
SIS - symbian file ()
SIT - Archive (Macintosh) (STUFFIT)
SKI - ? ( ?)
SKP - Google SketchUp file ()
SKY - SYLK Spreadsheet file (used by Multiplan) ()
SL - S-Lang source code file ()
SLB - P-CAD library (symbols) (P-CAD)
SLB - Slide library (AutoCAD)
SLC - SALT (script from Telix) compiled code (Telix)
SLD - Slide (AutoCAD)
SLDPRT - Part (SolidWorks)
SLDASM - Assembly (SolidWorks)
SLDDRW - Drawing (SolidWorks)
SLI - Slide (MAGICorp Slide Service)
SLK - Microsoft Excel import format (Microsoft Excel)
SLK - SYLK Symbolic Link format data file (MultiPlan)
SLL - Sound data file ()
SLL - Static Link Library (PowerBASIC)
SLN - Microsoft Visual Studio Solution (Microsoft Visual Studio)
SLP - SLP command file created by SRCCOM (RT-11)
SLP - Localization project file (Sisulizer)
SLT - SALT Script Application Language for Telix script source (Telix)
SLV - Solution for any game (many)
SM - Maillist (SoftSpoken Mailer)
SM - Script (ScriptMaker)
SM - SMALLTALK source code file ()
SM - Text file (Samna Word)
SM - StepMania Step File (StepMania)
SMC - Super MagiCom SNES ROM image (Super MagiCom)
SMCLVL - Secret Maryo Chronicles Level (Secret Maryo Chronicles)
SMF - Fax (SMARTFAX)
SMF - 3D World Studio mesh files ()
SMK - Smacker Video Format (RAD Video) ()
SML - System Macro Library (RT-11)
SMM - Ami Pro Macro File (Ami Pro)
SMN - Font (ParaGraph's WorkScript format) ()
SMP - Sample (sound file) ()
SMP - Samplevision File (Samplevision)
SMPL - Data (Megahedron 3D object)
SMS - MSTS Sound management system file (MSTS)
SMT - Text file (Smart Ware II)
SN - Compressed song file (Sound Club editor)
SND - Digitized sound file (Macintosh/ATARI/PC)
SND - Power Chords drum sound file (Power Chord)
SNDB - SQLNotes database (SQLNotes)
SNG - Song (midi sound) (Midisoft Studio - Prism)
SNG - Saved game file for StarCraft (StarCraft)
SNO - SNOBOL4 source code file ()
SNP - Book-shelf for .BOO (READIBM)
SNP - Microsoft Access report snapshot ()
SNP - Output video format from Computer Eyes equipment ()
SNX - Saved game file for StarCraft: Brood War (StarCraft: Brood War)
SO - shared object, dynamically linked library (Unix, Linux)
SOAR - Soar Production file ()
SOF - Altera FPGA programming file (internal RAM) (Altera Quartus)
SOL - Solution e.g. game walkthroughs ()
SOL - Adobe Flash shared object ("Flash cookie") (Movie, film, video and multimedia file type) (Adobe Flash)
SOM - Network serial numbers (Quattro Pro)
SOM - Sort information (Paradox)
SON - Song (SBStudio II)
SOU - Temporary BATCH file (RT-11)
SOU - SBStudio II Sound File (SBStudio II)
SOU - Sound data (sound tool) ()
SP - Archive (unix) (SPLINT)
SPC - Program (Microsoft Multiplan)
SPC - Temporary file (WordPerfect for Win)
SPC - SNES SPC-700 Sound File (SNES games)
SPC - Spectroscopic data (scientific) (Thermo Scientific)
SPD - Scalable font (Speedo - Harvard Graphics 3.0)
SPF - Slide presentation file (EnerGraphics)
SPF - data (SQR Portable Format)
SPG - Glossary (Sprint)
SPI - Graphics (Siemens and Philips scanner) ()
SPIFF - Still Picture Interchange File Format ()
SPIN - Spin source file (Parallax Propeller Microcontrollers)
SPL - Archive (SPLINT)
SPL - Customized printer driver (Sprint)
SPL - Divided file segment (Slice)
SPL - Personal spell dictionary (Signature)
SPL - Print spooling file (Windows 3.x)
SPL - Sample ()
SPM - Data wp{wp}.spm (WordPerfect)
SPP - Printer file (Sprint)
SPR - Document letter (Sprint)
SPR - Generated executable screen file (FoxPro)
SPR - Sprite ()
SPR - Story Board sprites ()
SPS - Exported SyncBack profile (SyncBack)
SPS - Screen driver (Sprint)
SPS - SPSSx source code file (VAX/VMS)
SPT - Data support file (MITAC disk/system management utility pack) (MITAC disk/system management utility pack)
SPT - SPITBOL source code file ()
SPW - Worksheet (SigmaPlot)
SPX - Compiled executable screen file (FoxPro)
SPX - Ogg Speex bitstream[1] (Xiph.Org Foundation)
SQD - Squish message base (Squish)
SQI - Squish message base index (Squish)
SQL - Structured Query Language (Any SQL database)
SQLite - SQLite (Firefox SQLiteBrowser)
SQL - Squish message base lastread pointers (Squish)
SQM - Windows Live Messenger log file ()
SQN - Note file (SquareNote)
SQZ - Archive (SQUEEZE)
SQZ - FOXPRO Squeeze file (FOXPRO)
SRC - Source code (Aurora Compiler)
SRC - Multi-edit source (Multi-Edit)
SRC - Source (DataFlex)
SRF - Sun Raster File graphics file ()
SRP - Script (QuickLink)
SRT - Subtitle format (SubRip)
SS - Bitmap graphics (Splash)
SS - Screen saver (DN)
SSC - Celestia Solar System Catalog file (Celestia)
SSD - Datafile (SAS/PC)
SSF - Graphic file (SnagIt Studio File/PC)
SSG - Saved game (Simsig)
SSIF - Stereoscopic Interleaved file (Media playback devices / software that supports Blu-ray 3D)
SSP - Datafile (SAS Transport)
SSR - FLEXIT Singleshot Survey Raw Data file (FLEXIT)
SST - AVHRR graphic file ()
SSV - Spreadsheet viewer file ()
ST - Instrument library (Scream Tracker)
ST - SMALLTALK source code file (Little Smalltalk)
ST - Stamp (NeoPaint)
STA - Data file (Statistica)
STA - Saved state (Reflection 4.0)
STA - Stack (Spinmaker Plus)
STB - Symbol table file (RT-11)
STB - Stub library (Genus GX Kernel)
STC - Celestia Star Catalog file (Celestia)
STC - OpenOffice.org XML spreadsheet template (OpenOffice.org Calc)
STD - State Transition Diagram graphic file (Prosa)
STD - OpenOffice.org XML drawing template (OpenOffice.org Draw)
STEAMSTART - STEAMSTART file (Steam (software))
STF - Archive (SHRINKTOFIT)
STF - Setup Table File ()
STI - OpenOffice.org XML presentation template (OpenOffice.org Impress)
STK - eBook (Starebook)
STL - Stereolithography Interface Format ()
STL - Subtitle files EBU-standard ()
STM - Music format (4 channels) (Scream Tracker Module) (ST - DMP)
STM - State Transition Diagram model file (Prosa)
STO - Pascal stub OBJ file (Genus GX Kernel)
STP - Subtitler Project (Belle Nuit Subtitler)
STR - Gate3 table structure file ()
STR - Structure list object file (dBASE Application Generator)
STR - PlayStation video file ()
STS - Music format (Scream Tracker Song) (ST 2.0-2.3)
STS - Project status info (Microsoft C/C++)
STU - Studio Project (Pinnacle Studio (video editing software))
STUFF - EVE Online compressed file archive (CCP hf)
STW - Data file (SmartTerm for Windows)
STW - OpenOffice.org XML text document template (OpenOffice.org Writer)
STX - Electronic book (SmarText)
STX - Music format ()
STX - Tax form (CA-Simply Tax)
STY - Ami Pro Template (Style); used by other programs for `styles` (Ami Pro)
STY - Style library or sheet (many)
SU - Saurus source file ()
SU? - Packed mail (FTN software)
SUB - Subtitle format (SubViewer; Author David Dolinski)
SUC - Saurus byte-code file (Saurus VM)
SUF - Sony camera configuration file (setup.suf) (XDCAM-EX camcorders)
SUI - SUIT library (Simple User Interface Toolkit)
SUM - Summary ()
SUN - Sun rasterfile graphics file (Sun Microsystems)
SUO - Solution User Options (Microsoft Visual Studio)
SUP - Subtitle file (Blu-ray encapsulated container) (SupRip)
SUP - Supplementary dictionary (WordPerfect for Win)
SUR - Surface topography (in native "SURF" format) (MountainsMap)
SV4 - Saved Game File (RollerCoaster Tycoon)
SV6 - Saved Game File (RollerCoaster Tycoon 2)
SVC - Represents the ServiceHost instance hosted by Internet Information Services (Windows Communication Foundation)
SVD - Autosave file for document (Microsoft Word)
SVG - Autosave file for glossary (Microsoft Word)
SVG - Scalable Vector Graphics (many)
SVQ - MRC-Pro sequencers music format (Roland Corporation synths such as XP or Fantom series)
SVS - Autosave file for style sheet (Microsoft Word)
SVW - Super Video Windows (Conversion Artist)
SVX - Interchange, 8SVX/16SV (AWAVE)
SVY - FLEXIT Survey data (FLEXIT)
SW - Raw Signed Word (16bit) data (AWAVE)
SWF - Shockwave Flash (Macromedia)
SWG - SWIG source code (SWIG)
SWG - SWAG Pascal Snippets file (SWAG)
SWP - Document backup (Sprint)
SWP - Swap file ()
SWT - Hump Routes File (FYM)
SXC - OpenOffice.org XML spreadsheet (OpenOffice.org Calc)
SXD - OpenOffice.org XML drawing (OpenOffice.org Draw)
SXG - OpenOffice.org XML master document ()
SXI - OpenOffice.org XML presentation (OpenOffice.org Impress)
SXM - OpenOffice.org XML formula (OpenOffice.org Calc)
SXP - 3DS Process file (3D Studio)
SXW - OpenOffice.org XML text document (OpenOffice.org Writer)
SY1 - SmartPix symbol library (Ami Pro)
SY3 - Harvard Graphics format ()
SY3 - Symbol file (Harvard Graphics 3.0)
SYD - Backup of startup files created by QEMM (?) autoexec.syd ()
SYD - Sysedit backup file (Sysedit)
SYG - Monitor and handler files created by SYSGEN (RT-11)
SYM - Compiler symbolic information file ()
SYM - P-CAD component (symbols) (P-CAD)
SYM - Precompiled headers (Borland C++)
SYM - Program symbol table (Power C, Microsoft ILink incremental linker)
SYM - Symbol file (Harvard Graphics 2.0, Microsoft Windows SDK)
SYN - SDSC Synu image file (SDSC Image Tool)
SYN - Synonym file (Microsoft Word 5)
SYS - Datafile (SYGRAPH - SYSTAT - SPSS/PC)
SYS - System file - device driver or hardware configuration info (DOS)
SYW - Graphics file (symbol) (Harvard Graphics Win)
SYW - Yamaha SY-85/SY-99 Wave File (Convert (c) Villena)
SZPROJ - SZInstallSystem Project (SoftwareZator 2011 Standart Edition)

T - Archive without compression (tape) (tar)
T - TADS source ()
T - Tester symbol table (ReaGeniX code generator)
T?H - Turbo Help file (Pascal, C, Assembler, ...) (Borland Thelp)
T$M - AVG scan log files[2] (AVG)
T2B - Bookeen Cybook thumbnail (Cybook)
t2flow - Taverna 2 workflow definition (Taverna workbench)
T2L - True2Life file format (3D Internet content developers)
T44 - Temporary file for Sort or Index (dBASE IV)
T64 - Program (C64S emulator)
TAG - Query tag name (DataFlex)
TAH - Help file for Turbo Assembler (Borland C++)
TAK - Audio codec, Lossless audio file format (Winamp (+Plugin), foobar2000 (+Plugin), Media Player Classic - BE)
TAL - Adobe Type Align (Adobe)
TAL - Text illustration (TypeAlign)
TAP - Tape file (ZX Spectrum emulator by g.a.lunter)
TAR - Archive (TAR)
TAZ - Archive (WinZipNT - TAR - COMPRESS)
TB - Tab file (Virtual Desktop Tab) (Tabbery)
TB1 - Font file (Borland Turbo C)
TB2 - Font file (Borland Turbo C)
TBF - Fax (Imavox TurboFax)
TBK - FOXPRO template backup file (FOXPRO)
TBK - Memo backup (dBASE IV - FoxPro)
TBK - Toolbook (Asymetrix ToolBook)
TBL - Short for Table (used by many programs)
TBL - Aldus TableEditor file (TableEditor)
TBL - Gate3 table file ()
TBL - Graphics file (native format) (PageMaker TableEditor)
TBL - Table of values (OS/2)
TBR - Norton Desktop custom toolbar (NDW)
TBS - Text elements ?? (Textbausteine) (Microsoft Word)
TBX - Table (Project Scheduler 4 - TermBase eXchange (ISO 30042))
TBZ - Archive (WinZipNT - TAR - Bzip2)
TC - Configuration (Turbo C - Borland C++)
TCH - Help file (Turbo C - Borland C++)
TCL - Tool Command Language source code (Swat)
TCT - Drawing Template (TurboCAD for Windows)
TCW - Native Drawing File (TurboCAD for Windows)
TD - Config from Turbo Debugger (Turbo Debugger)
TD0 - Compressed disk image file (Teledisk)
TD1 - Multi-part disk image file (Teledisk)
TD2 - Configuration file (Turbo Debugger for Win32)
TDB - Database (TACT)
TDDD - Imagine Object File Format (Imagine)
TDF - Speedo font file ()
TDF - Typeface definition file (Speedo)
TDH - Help file for Turbo Debugger (Borland C++)
TDK - Keystroke recording file (Turbo Debugger)
TDR - Contens of Arvid tape ()
TDS - Symbol table (Turbo Debugger)
TDT - Thumbnail data (AVCHD)
TDW - Configuration file (Turbo Debugger for Windows)
TEC - Data (TECPLOT output)
TEC - TECO macro file ("compiled" form) (TECO)
TEF - Fax (Relisys TEFAX)
TEL - Host file (Telnet)
TEM - Input template (IconAuthor)
TEM - Turbo Editor Macro Language script (Borland C++)
TERM - Terminal File ()
TES - TECO macro file (source form) (TECO)
TET - Tetris results (DN)
TEX - Datasheet (Idealist)
TEX - TeX text file (Scientific Word - TeX)
TEX - Image (Slimtex)
TEXT - Text file ()
TF - Configuration (Turbo Profiler)
TFA - Area file (Turbo Profiler)
TFC - Catalogue file (Tobi's Floppy Cataloguer)
TFF - self executing TansForm dialogue (TansForm)
TFH - Help file for Turbo Profiler (Borland C++)
TFM - Tagged font metric file (Intellifont)
TFM - TeX Font Metric file (TeX)
TFS - Statistical information (Turbo Profiler)
TG1 - Project file (On Target)
TGA - Targa bitmap (Paint.NET, many raster graphics editors)
TGZ - Archive (WinZipNT - TAR - GNUzip)
TH? - Packed mail (FTN software)
THE - Windows'95 Desktop Theme (Microsoft Plus)
THM - Thumbnail or Theme File (Picture Publisher, PhotoMagic, Canon Digital Cameras, and Sony Digital Cameras create these Thumbnail files; also used for Sony Ericsson Theme File, for a cell phone)
THP - Nintendo proprietary video format (Various Nintendo games)
THR - ThredWorks Embroidery Format (Thred, Embroidermodder)
THS - Thesaurus dictionary (WordPerfect for Win)
TIB - Acronis True Image Backup (Acronis True Image)
TIC - FTN special file with assotiated file description (ALLFIX)
TIF - see TIFF ()
TIFF - TIFF (tagged image format file) bitmapped file (Alchemy - PhotoStyler -PageMaker - CorelDRAW)
TIGER - Tomb Raider binaries files (Ubi)
TIL - Fuzzy logic knowledge base (Togai InfraLogic Fuzzy-C Compiler)
TIP - Digital Signage Presentation (Tru-Designer, Tru-Player, Tru-Scheduler part of Tru-i Suite[3])
TIS - Tile set (MahJongg 3.0)
TJL - Backup file (VAXTPU editor)
TLB - Reference table (Bubble Chamber)
TLB - Text library (VAX)
TLB - Type library [1] (A binary file with information about a COM or DCOM object so other applications can use it at runtime. Created by Visual C++ or Visual Studio. Used by many Windows applications.)
TLC - Compiled Tool Command Language source code (Swat)
TLD - Disk Image (Teledisk)
TLG - Transaction Log (Intuit QuickBooks)
TLH - Typelib Generated C/C++ Header (Visual C++)
TLP - Project (TimeLine)
TLX - Website builder (Trellix)
TM2 - Typical Meteorological Year data (new) (Typical Meteorological Year)
TMF - Tagged Font Metric file (WordPerfect for Win)
TMF - TiVo movie (TiVo)
TMO - ZTG global optimizer default output file (Zortech C++)
TMO - HandsHigh ThoughtManager Outline (ThoughtManager Desktop)
TMP - Temporary file ((Several programs))
TMS - TeleMate compiled script (TeleMate)
TMY - Typical Meteorological Year data (old) (Typical Meteorological Year)
TMY2 - Typical Meteorological Year data (new) (Typical Meteorological Year)
TOC - Table Of Contents text file (ASCII) ()
TOCG - TorgaNET Diplomatic Cables (State Department of Torga)
TOK - Borland C++ 4.x reserved word list (BCW.EXE)
TOG - TorgaNET (TorgaNET database file)
TOPC - TopicCrunch SEO Project file holding keywords, domain and search engine settings (ASCII) ()
TORRENT - TORRENT File (BitTorrent clients (various))
TOS - Character file (The Only Sheet)
TOS - Self-extracting file archive (Atari ST) ()
TP - Session-state file (Turbo Profiler)
TP - Turbo Pascal cfg file (Turbo Pascal)
TP - TinkerPlots Document (TinkerPlots and Fathom Dynamic Data Software; documents contain data tables, graphs, text, pictures, etc.)
TP3 - Template (Harvard Graphics 3.0)
TPB - Downloadable PCL Soft font file backup (HiJaak)
TPC - File produced when an inter-Topicscape topic link file is exported to Windows (3D Topicscape)
TPF - Downloadable PCL Soft font file (HiJaak)
TPF - Print data in EMF format (ThinPrint)
TPH - Help file (Turbo Pascal)
TPL - Resident units library (Turbo Pascal)
TPL - Template file (GoldEd -ITrack)
TPL - Template (Harvard Graphics 2.0)
TPOLY - Data (TPOLY 3D object)
TPP - Protected Mode Units (Borland Pascal 7.0)
TPT - Digital Signage Presentation Template (Tru-Designer, Tru-Scheduler part of Tru-i Suite[3])
TPU - Borland Pascal DOS Mode Library (Borland Pascal)
TPU - Command file (VAXTPU editor) (VAXTPU editor)
TPW - Borland Pascal Windows Library (Borland Pascal)
TPW - Session-state file (Turbo Profiler for Windows)
TPZ - Archive (TAR - GNUzip)
TR - Man page input suitable for troff -man (cawf2.zip)
TR - Session-state settings (Turbo Debugger for DOS)
TR2 - Session-state settings (Turbo Debugger for Win32)
TRC - Debug support file (Power CTrace)
TRASH - File found during a file scan as bugged (Windows)
TRE - Directory tree file (PC-Tools)
TRD - Datafile (TrID file identifier filetypes definitions package)
TRIA - Data (Greg Hood's ASCII Triangle)
TRIB - Data (Greg Hood's Binary Triangle)
TRIF - Tiled Raster Interchange Format ()
TRK - Track (i.e. video sequence), used by many games ()
TRM - Terminal settings (Windows 3.x)
TRN - Translation support file (Quattro - Clarion)
TRS - Executable file (Micrografx or password file)
TRS - WiSo Mein Geld 2007 ()
TRS - IBM Mainframe log file (TRSMAIN)
TRU - True Basic source file ()
TRW - Session-state settings (Turbo Debugger for Windows)
TRY - Typical Meteorological Year data (variant) (TRNSYS)
TS - MPEG Transport Stream (Various media players / software)
TS - Qt Linguist TS File (Trolltech Qt Linguist)
TS - TypeScript source file ()
TSE - Data (Light Map Maker ASCII Scene)
TSK - Microsoft Multimedia Task Application (Win95)
TSL - Exported Schedule (Tru-Scheduler part of Tru-i Suite)
TSM - Turbo Assembler Manual (TASM for OS/2)
TST - Printer test file (WordPerfect for Win)
TSV - Tab Separated Values ()
TTF - TrueType Font file ()
TU? - Packed mail (FTN software)
TUD - The Ultimate Draw file (The Ultimate Draw)
TUT - Tutorial ()
TV - Table view settings (Paradox)
TVF - Table view settings (dBASE)
TVn - Overflow file above insert point in Doc n (WordPerfect for Win)
TWF - Warp Map File (Geo Semiconductor, Inc eWarp Pro Development Took Kit)
TXC - Test Configuration Format ()
TXF - Tax eXchange Format ()
TXI - Support file (TeX)
TXT - Common name for ASCII text file ()
TXT - Tab-Delimited Text File (Microsoft Excel)
TXT - Document Extension (TextEdit)
TXW - Yamaha TX-16W Wave File (Convert (c) Villena)
TY - TiVo movie (TiVo)
TYM - Time Stamp (PageMaker 4) (PageMaker 4)
TZ - Archive (TAR - COMPRESS)
TZB - Archive (TAR - COMPRESS - BTOA)
TZL - Tanzzle pattern file (Tanzzle)
TZX - Tanzzle image file (Tanzzle)

U3D - Model file format (Ultimate 3D)
U3D - Universal 3D (Adobe Acrobat)
U8 - Sample ()
UB - Raw Unsigned Byte (8bit) data (AWAVE)
UC2 - Archive (UC II)
UCN - New archive (UC II)
UCS - Unknownsoft Service Pack (mainly for Shadow OS 2009) (Unknownsoft Computer Systems)
UDF - Filter (Aldus Photostyler)
UDO - Data (Moray User Defined Object)
UDIWWW - bookmark data (UdiWWW)
UDW - Raw Unsigned DWord data (AWAVE)
UE2 - Encrypted archive (UC II)
UFI - data (UFO CaptureV2 settings -)
UFO - graphic file (Ulead Photo Impact)
UHA - UHarc archive ()
UHS - Universal Hint System (binary file) ()
UI - Espire source code file (Geoworks UI Compiler Geos)
UI - Qt Designer's UI File (Trolltech Qt Designer)
UI - User interface (Sprint)
UIF - Long prompts for windows (WordPerfect for Win)
UIH - Espire header file (Geoworks UI Compiler Geos)
UL - ULAW audio file ()
ULD - Information about uploaded files (Procomm Plus - Datastorm Technologies, Inc.)
ULF - data (MRF Mapping Tool Kit Universal List Format)
ULT - Music (UltraTracker)
UMB - Backup file (MemMaker)
UMP - Umple UML Programming Language Format (Umple)
UMX - Unreal Music Package (Unreal Tournament)
UNF - Universal NES Image Interchange File Format ()
UNI - Datafile (Forecast Pro)
UNI - Music format (UNIMOD - MIKMOD)
UNIF - Universal NES Image Interchange File Format ()
UNV - Text file containing finite elements nodal coordinates and more See notes (Originally used by SDRC for its I-deas software; a lot of simulation software use it today)
UNX - Text file containing UNIX specific info ()
UOML - UniqueObject Markup Language (UOML) is a XML-based markup language ()
UOP - Uniform Office Format presentation ()
UOS - Uniform Office Format spreadsheet ()
UOT - Uniform Office Format text ()
UPD - Update data (dBASE)
UPO - Compiled update data (dBASE)
URL - Internet Shortcut (URL) (Windows Explorer)
URT - Utah Raster Toolkit ()
USE - Log file ()
USP - Printer font with USASCII extended character set (Adobe PageMaker)
USR - User database file (Procomm Plus - Turbo C++ tour)
UST - UTAU vocal track (UTAU)
UT! - datafile (uTorrent)
UTZ - Mobile Phone Theme (Sony Ericsson)
UU - Encoded file (ASCII) (UUENCODE/UUDECODE - Uuencoding)
UUE - Encoded file (ASCII) (UUENCODE/UUDECODE - Uuencoding)
UW - Raw Unsigned Word 16bit data (AWAVE)
UWF - UltraTracker WaveSample (UltraTracker)

V - Consistency check support file (ReaGeniX code generator)
V - Main input file for an image (Vivid 2.0)
V - Coq source file ()
V - Verilog source file ()
V1, V2, ... - Split parts of a whole file (JJSplit)
V8 - Covox 8bit file (AWAVE)
V10 - Data (Gouraud Shaded Vectors)
V2D - Voucher design file (Voucher management included in JFire (e.g. when printing a voucher))
VAI - multimedia (PhotoDub document)
VAL - Validity checks and referential integrity (Paradox for Windows)
VAL - Values list object file (dBASE Application Generator)
VALA - Sourcecode (Vala)
VAN - Animation (VistaPro)
VAP - Value Added Process (NetWare 2.xx)
VAP - Dialogic indexed adpcm voice file (VBASE/40)
VAR - Variable file (IconAuthor)
VB - Visual Basic .Net source file (Visual Basic .NET)
VBPROJ - Visual Basic .Net project file (Visual Basic .Net Express and Visual Studio 2003-2010 Project)
VBR - Visual Basic Custom Control file (Visual Basic)
VBS - VBScript script file (VBScript)
VBX - Visual Basic eXtension (Visual Basic)
VBZ - Visual Basic Setup Wizard Template (Setup Wizard)
VC6 - Graphite - 2D and 3D drafting (Ashlar-Vellum)
VC - Include file with color definitions (Vivid 2.0)
VC - Spreadsheet (VisiCalc)
VCA - Visual Clip Art ()
VCD - VideoCD ()
VCD - VirtualDrive CD Image File ()
VCD - Value Change Dump (Verilog) temporal database file ()
VCD - VisualCADD Drawing File ()
VCE - Visual CertExam File (VCE Exam Simulator)
VCLS - VocaListener voice scanner file (VocaListener Plug-in (Vocaloid3))
VCR - VCR drivers for Arvid ()
VCW - Visual workbench information (Microsoft Visual C++)
VCX - Spreatsheet (VisiCalc Advanced)
VDA - Targa bitmap graphics (many raster graphics editors)
VDI - Virtual Disk Image (VirtualBox)
VDO - Story Board video image (Story Board)
VDR - Drawing (ComputerEasy Draw)
VEG - Vegas Project (Sony Vegas)
VEW - GroupWise for Windows (Win)
VEW - View file (Clipper 5 - Lotus Approach)
VF0 - Database file (OTExpert 5)
VFA - FontLab Database file (FontLab)
VFD - Virtual Floppy Disk (Windows Virtual PC (among others))
VFM - Ventura Font Metrics file ()
VFM - Voting Form (Voter)
VFN - Voting Form for Customers (Voter)
VGA - VGA display driver ()
VGA - VGA display font ()
VGD - VGA display driver (Generic CADD)
VGM - Video Game Music audio format ()
VGR - Graphics file (Ventura Publisher)
VHD - Virtual Hard Disk (Windows Virtual PC (among others))
VI - LabVIEW Virtual Instrument (LabVIEW)
VI - Graphics file (Jovian Logic VI)
VI - Watcom editor script (VI.EXE)
VIA - VIA Document Project (VIA Text Editor)
VIC - see VICAR ()
VICAR - Graphics (Video Image Communication and Retrieval) ()
VID - Bitmap graphics (YUV12C M-Motion Frame Buffer) ()
VID - Graphics format (Word&Deed)
VID - MS-DOS Shell Monitor file (MS-DOS 5)
VID - Screen device driver (Word)
VIF - see VIFF ()
VIFF - Khoros Visualization Image File Format (SDSC Image Tool)
VIK - Graphics format (VIKING) ()
VIM - Vim script file (Vim text editor)
VINF - data (ReMPEG log file - frames info)
VIR - Virus or infected file ()
VIS - VIS graphics file ()
VLM - Vellum, Vellum 2D, Vellum Draft, Vellum 3D, DrawingBoard (Ashlar-Vellum)
VLM - Virtual Loadable Module (Netware)
VM - Virtual Memory file (Geoworks)
VMC - Virtual memory configuration (DOS/4GW PM 32X DOS Extender)
VMDK - Virtual Disk file (VMware)
VMF - Font characteristics (Ventura Publisher)
VMG - Nokia message file format (Text Message Editor (Nokia PC Suite))
VMS - Text file containing VMS specific info ()
VMT - Source Engine resource file (Source Engine)
VO - Include file with object definition (Vivid 2.0)
VOB - Video Object (DVD-R, DVD-RW)
VOC - Sound format (Creative Lab's Sound File) (PlayVoc)
VOF - Object folder (VZ Programmer)
VOP - Visual Orangator Project ()
VOP - Visual OTTHYMO Project ()
VOX - Dialogic adpcm file (AWAVE, CoolEdit)
VP - 3DS Video posting (3D Studio)
VPF - Vector Product Format ()
VPG - Graphics file (VPGraphics)
VPH - Virtual Pascal Help (VP/OS2)
VPI - Virtual Pascal Unit (VP/OS2)
VPM - Garmin Voice Processing Module ()
VPP - Visual Paradigm Project (Visual Paradigm for UML)
VQA - Vector Quantized Animation (The Legend of Kyrandia)
VQM - Hardware description language (Altera)
VRM - Overlay file (QuattroPro)
VRM - Visual rexx source (WATCOM VREXX)
VRML - Virtual Reality Modeling Language (NetScape)
VRP - Project (WATCOM VX?Rexx)
VRS - Video Resource e.g. video device driver (WordPerfect)
VS - Vellum Solids (Ashlar-Vellum)
VS - Include file with surface definition (Vivid 2.0)
VSD - Diagram (Shapeware Visio)
VSD - Visio drawing (Visio)
VSM - Visual Simulation Model (VisSim)
VSP - Sprite (SPX)
VSQ - Vocal synthesizer track data (Vocaloid2, Vocaloid3)
VSQX - Vocal synthesizer track data (Vocaloid3)
VSS - SmartShapes file (Shapeware Visio)
VSS - Visio Template (Visio)
VST - Truevision Vista graphics (many raster graphics editors)
VST - Visio Template (Visio)
VSTO - Microsoft Office add-in file (Microsoft Visual Studio)
VTF - Source Engine resource file (Source Engine)
VUE - Animation (3D Studio)
VUE - View (dBASE IV - FoxPro)
VW - Text file (VolksWriter)
VWR - File viewer file (PC Tools)
VWX - CAD File (VectorWorks 2008)
VXD - Windows 3.x virtual device driver (Windows 3.x)
VZT - Temporal database file (GTKWave data file)

W - Word chart file (APPLAUSE)
W01 - Yamaha SY-series wave files (AWAVE)
W01 - Yamaha TX16W wave file (AWAVE)
W30 - Printer font (AST TurboLaser - Ventura Publisher)
W31 - Startup file (Windows 3.1)
W3A - Warcraft III Abilities Export File (Contained in a Warcraft III map)
W3B - Warcraft III Destructables Export File (Contained in a Warcraft III map)
W3D - Warcraft III Doodads Export File (Contained in a Warcraft III map)
W3D - Westwood 3D object format (3D models used in Renegade and Generals)
W3D - Shockwave 3D object format ()
W3G - Warcraft III Replay File (File for Warcraft III)
W3H - Warcraft III Buffs Export File (Contained in a Warcraft III map)
W3M - Warcraft III Map (File for Warcraft III: Reign of Chaos)
W3N - Warcraft III Campaign (File for Warcraft III: The Frozen Throne)
W3O - Warcraft III Object Data Export File (Contained in a Warcraft III map)
W3P - Warcraft III Save (Save File for Warcraft III)
W3Q - Warcraft III Upgrades Export File (Contained in a Warcraft III map)
W3T - Warcraft III Item Export File (Contained in a Warcraft III map)
W3U - Warcraft III Unit Export File (Contained in a Warcraft III map)
W3V - Warcraft III Save (Save File for Warcraft III)
W3X - Warcraft III Expansion Map (File for Warcraft III: The Frozen Throne)
W3Z - Warcraft III Save (Save File for Warcraft III)
W40 - renamed system files (AUTOEXEC.BAT, COMMAND.COM, CONFIG.SYS,DBLSPACE.BIN.DRVSPACE.BIN,MSDOS.SYS) of Windows version (Windows 95, 98, ME (dual-boot feature))
W44 - Temporary file for Sort or Index (dBASE)
W95 - Something for Windows95 (Win95)
WAD - Where's All the Data? (Doom - Doom2)
WAD - Nintendo proprietary format for Wii channels, menus, etc. (Nintendo Wii)
WAG - Yard Contents File (FYM)
WAI - Warcraft III AI Data File (Warcraft III AI Data File)
WAR - Java Web Archive (A Java file format used to package and deploy web applications)
WAS - ProComm Script File (source code) (ProComm)
WAV - Sound format (Microsoft Windows RIFF WAVE) (Media Player)
WAX - TVTonic WAX video packaging (Wavexpress TVTonic)
WAX - ProComm compiled script (ProComm)
WAX - Windows Media Audio Shortcut (Windows Media Player (Windows Media Audio Redirector)[4])
WB1 - Notebook (Quattro Pro)
WB2 - Spreadsheet (Quattro Pro)
WBF - Microsoft Windows Batch File (Catch)
WBK - Document/workbook or Microsoft Word backup file (WordPerfect for Win or Microsoft Word)
WBT - Norton Desktop (Norton Desktop)
WBT - Wilsonware Batch file (Winbatch)
WCD - Condes Event Data file (Condes)
WCD - Macro token list (WordPerfect for Win)
WCH - WordPerfect Macro Facility (WP)
WCM - Data transmission file (Microsoft Works)
WCM - Macro (WordPerfect for Win)
WCP - Product information description (WordPerfect for Win)
WD - InfoSelect Data file ()
WDB - Database (Microsoft Works)
WDM - Admin tool connection definition (War FTP)
WE? - Packed mail (FTN software)
WEB - WEB source code file (Web Easy Professional)
WebOOGL - Web Object Oriented Graphics Library ()
WFB - Turtle Beach WaveFront Bank (AWAVE)
WFD - Turtle Beach WaveFront Drum (AWAVE)
WFM - Form object (dBASE Form Designer)
WFN - Font (CorelDRAW)
WFP - Turtle Beach WaveFront Prog. (AWAVE)
WFT - Web Family Tree (GRAMPS)
WFX - Data file (Winfax)
WG1 - Worksheet (Lotus 1-2-3/G)
WG2 - Worksheet (Lotus 1-2-3 for OS/2)
WID - Width table (Ventura Publisher)
WIFI - Torga OS Wifi Settings Database (14th Information Division (Torga))
WIKI - Wiki markup (various flavors) (Wikis)
WIM - Windows Imaging Format (ImageX)
WIN - Window file (FoxPro - dBASE)
WIREFRAME - Data (EMSE mesh)
WIX - Windows Installer XML (WiX)
WIZ - Page wizard (Microsoft Publisher)
WK1 - Spreadsheet (Lotus 1-2-3 version 2.x - Lotus Symphony 1.1+)
WK3 - Spreadsheet (Lotus 1-2-3 version 3.x)
WK4 - Spreadsheet (Lotus 1-2-3 version 3.4)
WKB - Document (WordPerfect for Win)
WKE - Spreadsheet (Lotus 1-2-3 educational version)
WKF - VISI Working file (Vero Software)
WKI - Spreadsheet format (Lotus 123 2x)
WKQ - Spreadsheet (Quattro)
WKS - Spreadsheet (Lotus 1-2-3 version 1A - Lotus Symphony 1.0, Microsoft Works)
WKS - Workspace (Xlisp)
WKZ - Spreadsheet format (Dos Navigator)
WLK - Graphics (Virtus Walkthrough)
WLK - Walk Through for any game (many)
WMA - Windows Media Audio audio file ()
WMC - Backup of startup files by Windows MathCad autoexec.wmc (MathCad)
WMC - Macro file (WordPerfect for Win)
WMC - Text file (WordMARC)
WMDB - Windows Media Player database (Windows Media Player)
WMF - Windows MetaFile vector graphics ()
WMO - WoW Map Object (Blizzard Entertainment games (World of Warcraft/Warcraft series))
WMP - Graphics (Windows Magic Icon Palette) ()
WMV - Windows Media Video video file ()
WN - Text (NeXT WriteNow)
WNF - Corel Draw Font File (CorelDraw)
WOA - Swap file (Windows 3.x)
WOC - Organization (Windows OrgChart)
WOW - Music (8 channels) (Grave Mod Player)
WP - Word Perfect Format (WP)
WP5 - Document (WordPerfect 5.x)
WPD - Document (WordPerfect 6.0 - PFS:WindowWorks)
WPD - Windows printer driver (uninstallable) (Windows)
WPF - Fax (WorldPort)
WPF - Form (WordPerfect)
WPG - WordPerfect Graphics vector graphics (DrawPerfect)
WPJ - Watcom C/C++ IDE project (IDE.EXE)
WPK - Macros (WordPerfect for Win)
WPL - MediaRack Wave Playlist (MediaRack)
WPL - Windows Media Playlist (Windows Media Player)
WPM - Macros (WordPerfect)
WPS - Text document (Microsoft Works)
WQ! - Compressed spreadsheet (Quattro Pro)
WQ1 - Spreadsheet (Quattro Pro)
WR1 - Spreatsheet (Lotus Symphony 1.1 - 1.2 - 2)
WRD - Template (Charisma)
WRI - Write editor format (Write - WinWord)
WRK - Spreadsheet (Lotus Symphony 1.0)
WRL - VRML file ()
WRP - Archive (Amiga WARP)
WRS - Windows Resource e.g. might indicate error if word cannot open (WordPerfect for Win)
WS - APL Worksheet ()
WS - Text file (WordStar 5.0-6.0)
WS2 - Text file (WordStar 2000)
WSD - Document (WordStar)
WSF - Windows Script File (Microsoft Windows Script Host)
WSP - Workspace (Fortran PowerStation)
WSQ - Wavelet-packet Scalar Quantization Format ()
WSRC - X-wais source ()
WST - Text file (WordStar)
WTR - Working Timetable rules file (Simsig)
WTT - Working Timetable timings file (Simsig)
WTF - World of Warcraft Data File (World of Warcraft)
WTF - WinTaper Data ()
WWB - Button bar for document window (WordPerfect for Win)
WWF - WWF Document Format ()
WWK - Keyboard layout (WordPerfect for Win)
WXH - Program/Script File (WaxHtml Web Programming Language)
WXP - Document (EXP for Windows)
WZ - Wizet game archive file (Wizet/Nexon MapleStory)
WZA - Encrypted archive file (Department of Defense Encryption Wizard (Public Edition))

X - Archive (X1.EXE)
X - AVS X image file (SDSC Image Tool)
X - DirectX 3D object ()
X - LEX source code file ()
X - XBasic Source code file (Xbasic)
X3D - x3d and xdart Formats ()
XA - XA audio file (used in SimCity 3000 by Maxis, also by Sony PlayStation)
XAR - Xara graphics file (Files created by Xara Photo & Graphic Designer (formerly Xara Xtreme and Xara Studio); early versions used the extension ART)
XBE - Xbox Executable (Xbox)
XBM - X11 Bitmap graphics file ()
XLBL - extensible Business Reporting Language (Business Reporting)
XCF - Gimp image file (The Gimp)
XCK - Extended crack file (usually text) ()
XCL - Xtree for Windows Script file (Xtree for Win)
XDF - OS/2 extended disk format image (XDFCOPY.EXE)
XDM - Directory Manipulator for 32-bit Protected Mode (Xenotech Research Labs)
XE - Xenon - for Associative 3D Modeling (Ashlar-Vellum)
XEX - Xbox 360 Executable File ()
XFN - Printer font (Xerox 4045 - Ventura Publisher)
XFR - Ventura Publisher Bitmap Editor Font file ()
XFT - 24 pin printer font (ChiWriter)
XI - Fast Tracker 2 instrument file (AWAVE)
XI - Fastracker 2.0 Instrument File (Fastracker 2.0)
XIF - Xerox Image Format (Pagis Pro 2.0 and 3.0)
XLA - Add-in macro sheet (Microsoft Excel)
XLA - XLib Archive (xlibpas2.zip)
XLB - Microsoft Excel Toolbar (Microsoft Excel)
XLC - Microsoft Excel Chart (Microsoft Excel)
XLD - Microsoft Excel Dialog (Microsoft Excel)
XLF - Extensible LADAR Format (LadarSIM)
XLK - Microsoft Excel Archive (Microsoft Excel)
XLL - Microsoft Excel Dynamic Link Library (Microsoft Excel)
XLM - Microsoft Excel Macro File (Microsoft Excel)
XLS - Microsoft Excel Spreadsheet (Microsoft Excel)
XLSB - Microsoft Excel 2007 Binary Workbook (BIFF12)(Spreadsheets) (Microsoft Excel 2007 (see Microsoft Office 2007 file extensions))
XLSM - Microsoft Excel 2007 Macro-Enabled Workbook (Spreadsheets) (Microsoft Excel 2007 (see Microsoft Office 2007 file extensions))
XLSX - Office Open XML Workbook (Spreadsheets) (Microsoft Excel 2007 (see Microsoft Office 2007 file extensions))
XLT - Microsoft Excel Template (Microsoft Excel)
XLT - Translation table (Lotus 1-2-3 - Symphony - Procomm Plus)
XLV - Microsoft Excel Module (Microsoft Excel)
XLW - Microsoft Excel Workbook (Microsoft Excel)
XM - Fast Tracker 2 extended module (AWAVE, Mod4Win, FastTracker, ImpulseTracker)
XM - Music format (FastTracker - Cubic Player)
XMC - Assisted contact lists file format, based on xml and used in kindergartens and schools (Classmates iPhone app)
XMOD - Monarch Model (Monarch Professional)
XMI - Compressed eXtended MIdi music ()
XML - eXtensible Markup Language file ()
XMF - eXtensible Music Format ()
XMPZ - XML Miradi Project Zipfile (Miradi)
XMV - video (Xbox)
XNF - Standard Network File form ()
Xnn - Secondary indexes (Borland Paradox)
XOF - RenderMorphics ()
XP - eXtended Pattern (FastTracker 2.0)
XPL - X-Plane system file (Laminar research)
XPM - X11 Pixel Map graphics file ()
XPO - Microsoft Dynamics AX Export file ()
XPS - Open XML Paper Specification / OpenXPS (open standard document format initially created by Microsoft and similar in concept to Adobe PDF files)
XQT - Executable file (Waffle)
XQT - Macro sheet (SuperCalc)
XRF - Cross-reference file ()
XSF - data (Microsoft InfoPath file)
XSPF - XML Sharable Playlist Format ()
XTB - External translation table (LocoScript)
XTP - XTreeGold overlay (XTreeGold)
XVF - Xyngo Video File (Xyngo Video Board)
XWD - Xerox DocuWorks file (RTF internal?) (DocuWorks)
XWD - X Window System window dump image graphics file (SDSC Image Tool)
XWK - Keyboard mapping (Crosstalk)
XWP - Session (Crosstalk)
XWP - Text file (Xerox Writer)
XX - XX-encoded file (ASCII) (XXDECODE)
XXE - XX-encoded file (ASCII) (XXDECODE)
XXX - Singer Embroidery Format (Embroidermodder)
XY - Text file (XY Write)
XY3 - Text file (XYWrite III)
XYW - Text file (XyWrite III)
XYZ - Molecular coordinates (XMol, RasMol)
XZ - a lossless data compression file format incorporating the LZMA/LZMA2 compression algorithms. (xz)

Y - Archive (Amiga) (Yabba)
Y - YACC grammar file (Yacc/Bison)
YAL - Data custom/nature.yal (Arts & Letters)
YC - Archive (YACC (YAC.EXE))
YLIB - Yookoo Music Library Backup File (Yookoo Media Player)
Ynn - Secondary index (Borland Paradox)
YMP - Yast Meta Package (YAST2 (SUSE Linux Package Manager))
YOOKOO - Yookoo Playlist (Yookoo Media Player)
YST - Data (YASRT Raytracer scene)
YRD - Yard Tracks File (FYM)
YUV - Graphics format (YUV) ()
YY - Bison grammar file (Bison)
YZ - Archive (YAC)

Z - Archive (WinZipNT - COMPRESS - PACK)
Z01-Z99 - Split WinRAR Archive ()
Z2S - Zoo Tycoon 2 saved game (Any game in the Zoo Tycoon 2 series)
Z3 - Infocom game module ()
Z3D - Zmodeler-file (Zmodeler 1 & 2)
Z64 - Nintendo 64 ROM (Project64 Nintendo 64 emulator)
Z80 - Snapshot (ZX Spectrum emulator by g.a.lunter)
ZAD - ZFax digitized voice file (ZFax)
ZARGO - UML model project file (ArgoUML)
ZCC - Cutpath for Zund digital cutting systems (Zund Cut Center)
ZDG - Compressed ZiffNet text document (Zview)
ZED - BitTorrent Link (Podmailing)
ZER - Data file ()
ZIP - Archive (PKZip - WinZip - Mac OS X)
ZOO - Zoo Tycoon saved game (Any game in the Zoo Tycoon (first) series)
ZUR - High level compressed file ()
ZUZ - Cost estimating file (ZUZIA ZUZIAbim)
ZS - Script for Minecraft mod MineTweaker[5] (Minetweaker Minecraft Mod)
ZYP - Reason Subtractor Patch File (Propellerhead Reason)
ZZT - ZZT World (Any world created using the ZZT editor)