List of filename extensions (A–E) explained

This alphabetical list of filename extensions contains extensions of notable file formats used by multiple notable applications or services.

A

Ext.	Description	Used by
	Archive file	ar (Unix)
	Advanced Audio Coding file	iOS, Nintendo DSi, Nintendo 3DS, YouTube Music
^[1]	Microsoft Access Database	Microsoft Access Database (Open XML)
^[2]	Microsoft Access Data Type Template	Microsoft Access
ACO	Adobe color palette format (.aco)^[3]	Adobe Photoshop^[4]
	Abrechnungsdatentransfer, an xDT application	Healthcare providers in Germany
	Document	Archetype Designer
	Amiga Disk Zipped (See Amiga Disk File)	GZip
	Agda (programming language) source file	Agda typechecker/compiler
	ArcView ASCII grid
	AutoHotkey script file	AutoHotkey
^[5]	Adobe Illustrator Artwork	Adobe Illustrator
^[6]	Audio Interchange File Format	professional audio processing applications and on Macintosh^[7]
	Compressed Audio Interchange File Format
	APL programming language file transfer format file
^[8] ^[9]	Additive Manufacturing File Format	Computer Aided Design Software
	System image file	ACTOR
^[10]	AutomationML	AutomationML Group
	Compressed and packed AutomationML file	AutomationML Group
	AMPL source code file	AMPL
	Adaptive Multi-Rate audio
	Actions Media Video
^[11]	Animation cursors for Win	Win95 - WinNT
	Annotations of old Windows Help file	Windows 3.0 - XP
	Monkey's Audio (Lossless)	audio media players
	Android application package	Android
APK	Alpine Linux Package	Alpine Linux and derivatives
^[12]	ARC (file format)
^[13]	Gerber format	Cadence Allegro, EAGLE
^[14]	ASP.NET global application file
	ASP.NET User Control
^[15]	Advanced Streaming Format (Compressed Windows audio/video)	Microsoft Corporation
	ASP.NET handler file
	Assembler language source	TASM, MASM, NASM, FASM
	Active server page extended file	Microsoft Corporation
^[16]	Advanced Stream Redirector file, redirects to an ASF file (see ASF)	Microsoft Corporation
^[17]	Coco/R LL(1) formal grammar	Coco/R
^[18]	Atrac 3 Sound/music file	All Sony devices and programs with the Atrac 3+ specification
AU	audio file^[19]
^[20] ^[21]	Audio Video Interleave	Video for Windows
	AV1 Image File Format
	AWK script/program	awk, GNU Awk, mawk, nawk, MKS AWK, Awka (compiler)
	DirectShow Filter	Microsoft Corporation (Video Players)
^[22]	lightweight geodatabase	ESRI ArcPad

B

Ext.	Description	Used by
	BASIC language source
	bc arbitrary precision calculator language file	Unix bc tool
B64	base64 binary-to-text encoding^[23]
	backup	various
	Broker Archive. Compressed file containing number of other files for deployment.^[24]	IBM App Connect
	BASIC language source	QuickBASIC - GW-BASIC - FreeBASIC - others
	Batch file	MS-DOS, RT-11, DOS-based command processors
	Glyph Bitmap Distribution Format, a format used to store bitmap fonts.	Adobe
	Behandlungsdatentransfer, an xDT application	Healthcare providers in Germany
	Executable bytecode file in fat binary format	BEAM (Erlang virtual machine)^[25]
BIB	Bibliography database	BibTex
BIN	binary file	Every OS
BLEND	Blender project file	Blender
	UIQ3 Phone backup
^[26]	OS/2 or Win graphics format (BitMap Picture)	QPeg - CorelDraw - PC Paintbrush - many
BPS	WPS backup file^[27]	Microsoft Word, Microsoft Works
BSON	JSON-like binary serialization^[28]	MongoDB
BSP	Binary space partitioning tree file	Quake-based game engines
BYU	3D geometry format^[29]	CAD systems
^[30]	Archive	bzip2

C

Ext.	Description	Used by
	C-- language source	Sphinx 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.^[31]	Watcom C/C++, Borland C/C++, gcc and other C compilers
	Unix file archive	COMPACT
	C++ language source
	C++ language source
Config	Configuration file
	COMBOOT Executable (32-bit)	SYSLINUX
^[32]	Cabinet archive	Windows 95 and later, many file archivers
^[33]	COBOL language source
	COMBOOT Executable (incompatible with DOS COM files)	SYSLINUX
	C++ language source
	ASP.NET class diagram file
^[34]	Common Data Format
^[35]	Computable Document Format	Mathematica
CDP^[36]	Trainz Railroad Simulator Content Dispatcher Pack	Trainz Railroad Simulator
^[37]	Vector graphics format (drawinF	CorelDraw
CDXML	MIME type: chemical/x-cdxmlXML version of the ChemDraw Exchange format, CDX.^[38]
^[39]	Security certificate	Microsoft Windows
^[40] ^[41]	Computer Graphics Metafile vector graphics	A&L - HG - many
^[42]	Compiled Help File	Microsoft Windows, Help Explorer Viewer
^[43]	ChordPro lead sheet (lyrics and chords)	ChordPro and similar tools
	Decrypted Nintendo 3DS ROM cartridge	Nintendo 3DS
^[44] ^[45]	Crystallographic Information File	RasMol, Jmol
^[46]	Java class file	Java
CLS	ooRexx class file	ooRexx
	Command Prompt batch file	Microsoft Windows NT based operating systems
^[47]	executable programs	CP/M-86 operating system
CML	Chemical Markup Language, for interchange of chemical information.^[48]
^[49]	Celestia Model	Celestia
^[50]	CNR IDL	MITRE
CNOFF	3D object file format with normals (.noff, .cnoff)^[51] NOFF is an acronym derived from Object File Format. Occasionally called CNOFF if color information is present.^[52]
^[53]	COBOL language source	GnuCOBOL
^[54]	Coefficient file	Xilinx ISE
COFF	3D object file format (.off, .coff)^[55] OFF is an acronym for Object File Format. Used for storing and exchanging 3D models. Occasionally called COFF if color information is present.^[56]
COL	DIMACS graph data format.^[57]
	DOS program	DOS-
	ASP.NET precompiled stub file
^[58]	Compressed image	Cartesian Perceptual Compression
	cpio archive file	cpio
^[59]	Control panel file	Windows 3.x
	COBOL source copybook file
^[60]	Raw image format	Canon digital cameras
CR3^[61]	Raw image format	Canon R series cameras
^[62]	CRAM index
CRAFT	Holds Spacecraft Assembly information	Kerbal Space Program
	Security certificate	Microsoft Windows
^[63]	C# language source
^[64] ^[65]	C# project file	Microsoft Visual Studio
^[66]	Cascading style sheet
^[67]	Compiled Shader Object, extension of compiled HLSL	High-Level Shading Language
^[68]	Comma Separated Values text file format (ASCII)
CUB	Used by electronic structure programs to store orbital or density values on a three-dimensional grid.^[69]
CUBE	same as .cub
	Non-animated cursor (extended from ICO)	Windows

D

Ext.	Description	Used by
	D Programming Language source file	DMD
	Directory containing configuration files (informal standard)	Unix
	Direct Access Archive
	COLLADA file
	Data file	Digital Anchor
	Dart (programming language) source file
	AMPL data file	AMPL
	LDraw (Sub)Part File, 3D Model	LDraw
	Data	RSNetWorx Project
	Data file in special format or ASCII
	Database file	Clarion (programming language)
	Norton Utilities disc image data. It saves Boot sector, part of FAT and root directory in image.DAT on same drive.	Norton Utilities
	Optical disc image (can be ISO9660, but not restricted to)	cdrdao, burnatonce
	Video CD MPEG stream
	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
	Dynamic source	ATS
	DarkBasic source code
	Database Connection configuration file	AbInitio
DBF	Native format of the dBASE database management application.^[70]
	Debugger script	DOS debug - Watcom debugger
	Symbolic debugging information	Microsoft C/C++
	deb software package	Debian Linux and derivatives
DEM	digital elevation model (DEM) including GTOPO30 and USGSDEM. GTOPO30 is a distribution format for a global digital elevation model (DEM) with 30-arc-second grid spacing.^[71] USGSDEM is the standard format for the distribution of terrain elevation data for the United States.^[72]
	CAD Drawing	Bentley Systems, MicroStation and Intergraph's Interactive Graphics Design System (IGDS) CAD programs
	Digital Imaging and Communications in Medicine (DICOM) bitmap	DICOM Software (XnView)
	Data Interchange Format	Visicalc
	Output from [diff] command - script for Patch command
	Directory listing (ls format)	Dired
	DivX media format
	Apple Disk Image	macOS (Disk Utility),
	memory dump file (e.g. screen or memory)
	Dimension model format	Adobe Dimension^[73]
^[74]	Digital Negative, 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
^[75]	A Document, or an ASCII text file with text formatting codes in with the text; used by many word processors	Microsoft Word and others
	Microsoft Word Macro-Enabled Document	Microsoft Word
^[76]	Microsoft Word Document	Microsoft Word
	Microsoft Word document template	Microsoft Word
	Office Open XML Text document template	Microsoft Word
^[77] ^[78]	Digital Picture Exchange
	Dirac format video
^[79]	Celestia Deep Space Catalog file	Celestia
DTA	Stata database transport format.^[80]	Stata
^[81]	Document Type Definition
^[82]	Data version control yaml pointer into blob storage
	Autodesk Design Web Format	Design Review
^[83]	Drawing	AutoCAD, IntelliCAD, PowerCAD, Drafix, DraftSight etc.
DX	same as JDX and JCM.
^[84]	Drawing Interchange File Format vector graphics	AutoCAD, IntelliCAD, PowerCAD, etc.

E

Ext.	Description	Used by
	E language source code	E
	EnCase Evidence File chunk	EnCase Forensic Analysis Suite entity
	ArcInfo interchange file	GIS software
	2-dimensional vector graphics file	Editor included in JFire
	A file format developed by ASTM International for storing point clouds and images	Most software that enables viewing and/or editing of 3D point clouds
	versions of DOS system files (AUTOEXEC.BAT, COMMAND.COM, CONFIG.SYS, WINBOOT.SYS, etc.) for an emergency boot disk	Windows 98, ME
	Source code	eC
	Error-checking file	dvdisaster
	Ensoniq EPS disk image	AWAVE
	European data format	Medical timeseries storage files
EFI	Extensible Firmware Interface
	EIS Spectrum Analyser Project	EIS Spectrum Analyser
	Emacs Lisp source code file	Emacs
	Byte-compiled Emacs Lisp code	Emacs
ELF	Executable and Linkable FileEurekaLog File (contains details of an exception)	UnixEurekaLog (https://www.eurekalog.com/)
	Outlook Express Email Message	Windows Live Mail, Outlook Express, Microsoft Notepad
	E language source code (maker)	E
	Microsoft Enhanced Metafile
	Email conforming to RFC 5322;^[85] Stationery Template	Email clients Outlook Express
	Microsoft Enhanced Metafile compressed with ZIP	Microsoft Office suite
	Embedded OpenType
	GUI wireframe/prototype project	Prikhi Pencil, Evolus Pencil
	Award BIOS splash screen	Award BIOS, XnView
	Encapsulated PostScript	CorelDraw - PhotoStyler - PMView - Adobe Illustrator - Ventua Publisher
	Electronic Publication (e-Reader format)	Okular (Linux) - Apple Books - Sony Reader - Adobe Digital Editions - Calibre (LMW)
EU4	Europa Universalis 4 save game file	Europa Universalis 4
	Erlang source code file
	ECMAScript 6 file
	Data file of "esCAD pcb", PCB Pattern Layout Design Software	esCAD pcb provided by Electro-System
	Data file of "esCAD sch", Drawing Schematics Diagram Software	esCAD sch provided by Electro-System
	Windows Imaging Format	ImageX, DISM, 7-Zip, wimlib
	event trace log file	Microsoft^[86] ^[87]
	Windows Event log file	Microsoft Windows NT 4.0 - XP; Microsoft Event Viewer
	Windows Event log file XML structured	Microsoft Windows Vista, 7, 8; Microsoft Event Viewer
	Elixir source code file	Elixir programming language running on BEAM (Erlang virtual machine)^[88]
	Directly executable program	DOS, OpenVMS, Microsoft Windows, Symbian or OS/2
	Drawing File format	Drawing Express
	Melco Embroidery Format	Embroidermodder
EXR	OpenEXR raster image format (.exr). Used in digital image manipulation for theatrical film production. EXR is an acronym for Extended Dynamic Range. Stores 16 bit per pixel IEEE HALF-precision floating-point color channels. Can optionally store 32-bit IEEE floating-point "Z" channel depth-buffer components, surface normal directions, or motion vectors.^[89]
	Elixir script file	Interactive Elixir (IEx) shell^[90]

See also

• List of filename extensions
• List of file formats

External links

• File Extension Resource
• The File Extensions Resource
• File information site
• File format finder
• List of file types
• File format search engine

Notes and References

1. Web site: Which Access file format should I use?. 2020-09-13. microsoft.com.
2. Web site: Save and reuse database design elements . 29 October 2015.
3. Web site: Listing of All Formats .
4. Web site: ACO (.aco) . Wolfram Language & System Documentation Center.
5. Web site: What is a vector file?. 2020-09-12 . adobe.com.
6. Web site: AIFF-C Compression Types and Names . Tom Erbe . 1999 . 2010-03-21 . https://web.archive.org/web/20060620002145/http://shoko.calarts.edu/~tre/AIFFC/comptype.html . 2006-06-20.
7. Web site: AIFF (.aif, .aiff, .aifc) .
8. http://www.astm.org/Standards/ISOASTM52915.htm Specification for Data Exchange Format for Additive Manufacturing
9. https://www.iso.org/standard/67472.html Specification of AMF on ISO web page
10. Web site: AutomationML . 2020-09-13 . AutomationML e. V..
11. Web site: About animated cursors . 2020-09-14 . gdgsoft.com.
12. Web site: Arc File Format . Mike . Burner . Brewster . Kale . 2020-09-13 . 1996-09-15.
13. Web site: Gerber Format . 2020-04-09 . 2020-09-13 . ucamco.com .
14. https://docs.microsoft.com/en-us/previous-versions/2wawkw1c(v=vs.140) ASP.NET Web Project File Types
15. Web site: Overview of the ASF format . 2018-05-31. 2020-09-12. microsoft.com.
16. Web site: ASX Element . microsoft.com . 2018-05-31 . 2020-09-14.
17. Web site: Coco/R own DSL grammar. github.com.
18. Web site: ATRAC Developer's Interview. sony.net . 2020-09-12.
19. Web site: AU (.au) .
20. Web site: AVI File Format with OpenDML Extensions, Version 1.02. 2016-03-09. www.loc.gov. 2019-09-01.
21. Web site: AVI RIFF File Reference - Windows applications. stevewhims. docs.microsoft.com. en-us. 2019-09-01.
22. Web site: The ArcPad Team Blog: What is an ArcPad AXF?.
23. Web site: Base64 (.b64) .
24. Web site: Deploying integration solutions . ibm.com . 2021-05-18.
25. Web site: The Erlang Runtime System. happi.github.io. en. 2018-05-07.
26. Web site: Bitmap Storage . 2018-05-31 . 2020-09-12 . microsoft.com.
27. Web site: BPS File Extension - What is a .bps file and how do I open it?. fileinfo.com. en. 2018-10-12.
28. Web site: BSON (.bson) .
29. Web site: BYU (.byu) .
30. Web site: BZIP2 Format Specification . . 27 February 2022 .
31. Web site: Overall Options - Using the GNU Compiler Collection (GCC). 2020-06-27. gcc.gnu.org.
32. Web site: Cabinet Files . 2018-05-31 . 2020-09-13 . microsoft.com.
33. Book: Coughlan, Michael . Beginning COBOL for Programmers . Apress . 13 August 2014 . 400 . 978-1430262534 . 16 March 2014.
34. Web site: What is Common Data Format (CDF)? . 2020-09-13.
35. Web site: Computable Document Format . 2020-09-12. wolfram.com.
36. Web site: CDP File - What is it and how do I open it? . 2022-10-28 . file.org . en.
37. Web site: Trying to Open a .CDR File? . 2020-09-12.
38. Web site: CDXML (.cdxml) .
39. Web site: Certificate extensions explained . 2020-09-12 . digicert.com.
40. https://www.iana.org/assignments/media-types/image/ IANA Image Media Types
41. http://standards.iso.org/ittf/PubliclyAvailableStandards/index.html ISO/IEC 8632
42. Web site: Create a Help Project . 2020-09-12 . 2018-05-31.
43. Web site: Welcome to ChordPro! . 2020-09-12.
44. Hall SR, Allen FH, Brown ID . The Crystallographic Information File (CIF): a new standard archive file for crystallography . Acta Crystallographica Section A. 47 . 655–685 . 1991 . 10.1107/S010876739101067X . 6 . free .
45. Brown ID, McMahon B . CIF: the computer language of crystallography. Acta Crystallographica Section B: Structural Science . 58 . Pt 3 Pt 1 . 317–24 . 2002 . 10.1107/s0108768102003464. 12037350.
46. Web site: The class File Format . 2020-09-12 . oracle.com.
47. Web site: John C. . Elliott . Seasip.info . CP/M-86 executables (.CMD) . 2016-08-29 . live . https://web.archive.org/web/20161114135028/http://www.seasip.info/Cpm/cmdfile.html. 2016-11-14.
48. Web site: CML (.cml) .
49. Web site: Celestia's CMOD model format . 2020-09-12 .
50. Web site: MITRE's Combat Net Radio Initialization File . 2020-11-30 .
51. Web site: Listing of All Formats .
52. Web site: NOFF (.noff, .cnoff) .
53. Book: GnuCOBOL Programmer's Guide . July 2020 . Cutler . Gary . Coen . Vincent . 3.1 RC-1 . 10.1. Compiling Programs.
54. Web site: COE File Syntax . 2009 . xilinx.com.
55. Web site: Listing of All Formats .
56. Web site: OFF (.off, .coff) .
57. Web site: DIMACS (.col, .col.b) .
58. Web site: Technical Overview of Cartesian Perceptual Compression . 1999 . 2020-09-13.
59. Web site: Description of Control Panel (.cpl) Files . 2020-08-19 . 2020-09-12. microsoft.com.
60. Web site: Understanding What is stored in a Canon RAW .CR2 file, How and Why . 2020-09-12.
61. Web site: Quick look: Canon's new compressed Raw format . 2023-07-15 . DPReview.
62. Hsi-Yang Fritz. Markus. Leinonen. Rasko. Cochrane. Guy. Birney. Ewan. May 2011. Efficient storage of high throughput DNA sequencing data using reference-based compression. Genome Research. 21. 5. 734–740. 10.1101/gr.114819.110. 1549-5469. 3083090. 21245279.
63. Web site: Introduction to projects and solutions. 2020-11-17. 2021-05-06 . docs.microsoft.com.
64. Web site: Additions to the csproj format for .NET Core. 2019-04-28. 2020-09-12 . microsoft.com.
65. Web site: Understanding the project file . 2012-05-04. microsoft.com.
66. Web site: Cascading Style Sheets home page . 2020-09-12 . w3.org.
67. Web site: Compiling shaders home page . 2023-03-28 . w3.org.
68. Common Format and MIME Type for CSV Files . Shafranovich . Y. . . October 2005 . 4180 . 1 .
69. Web site: Cube (.cub, .cube) .
70. Web site: DBF (.dbf) .
71. Web site: GTOPO30 .
72. Web site: USGSDEM (.dem) .
73. https://helpx.adobe.com/dimension/user-guide.html/dimension/using/supported-file-types.ug.html Adobe Dimension User Guide
74. Web site: Digital Negative (DNG). Adobe Systems Incorporated.. 2018-07-30.
75. Web site: Microsoft Office Word 97 - 2007 Binary File Format Specification (*.doc). 2008. Microsoft Corporation .
76. Web site: Word Extensions to the Office Open XML (.docx) File Format. 2020-08-29 . 2020-08-18 .
77. Book: 10.5594/SMPTE.ST268-1.2014. 978-1-68303-083-6. SMPTE. ST 268-1:2014 - SMPTE Standard - File Format for Digital Moving-Picture Exchange (DPX).
78. Book: 10.5594/SMPTE.ST268-2.2018. 978-1-68303-161-1. SMPTE. ST 268-2:2018 - SMPTE Standard - Digital Moving-Picture Exchange (DPX) – Format Extensions for High Dynamic Range and Wide Color Gamut. 252588275 .
79. Web site: DSC Parameters recognized by Celestia v1.4.1 (and later) . 2020-09-13.
80. Web site: DTA (.dta) .
81. Web site: Extensible Markup Language (XML) 1.0 . 5 . 2008-11-26 . 2020-09-13 . w3.org.
82. Web site: Data Version Control.
83. Web site: Open Design Specification for .dwg Files . opendesign.com . 2020-09-13.
84. Web site: DXF Reference . February 2011. 2020-09-13. autodesk.com.
85. Web site: .EML File Extension. 2022-01-10. https://web.archive.org/web/20210812060630/https://fileinfo.com/extension/eml. 2021-08-12.
86. Web site: Windows Event Trace Log Sink . 2005-06-20 . Microsoft TechNet . Microsoft . 2017-02-08 . The Event Trace Sink provided with the Microsoft Enterprise Instrumentation Framework (EIF) produces event trace log (.etl) files [...]..
87. Compare: Book: Rea. Sara Morgan. Building Intelligent .NET Applications: Agents, Data Mining, Rule-based Systems, and Speech Processing. Addison-Wesley Microsoft Technology Series. 2005. Addison Wesley. 2005. 41. 9780321246264. 2017-02-08. Each call is logged to the Windows Event Trace Log and stored in a log file with an .etl (event log tracing) extension..
88. Web site: Modules and functions. elixir-lang.github.com. en-US. 2018-05-07.
89. Web site: OpenEXR (.exr) .
90. Web site: Erlang/Elixir Syntax: A Crash Course. elixir-lang.github.com. en-US. 2018-05-07.