# List of filename extensions (A–E)

This alphabetical list of filename extensions contains extensions of notable file formats used by multiple notable applications or services.
* 0-9
* A
* B
* C
* D
* E
* F
* G
* H
* I
* J
* K
* L
* M
* N
* O
* P
* Q
* R
* S
* T
* U
* V
* W
* X
* Y
* Z
* See also
* References

## A

| Ext. | Description | Used by |
| A | Archive file | ar (Unix) |
| AAC | Advanced Audio Coding file | iOS, Nintendo DSi, Nintendo 3DS, YouTube Music |
| ACCDB | Microsoft Access Database | Microsoft Access Database (Open XML) |
| ACCFT | Microsoft Access Data Type Template | Microsoft Access |
| ACO | Adobe color palette format (.aco) | Adobe Photoshop |
| ADT | Abrechnungsdatentransfer, an xDT application | Healthcare providers in Germany |
| ADX | Document | Archetype Designer |
| ADZ | Amiga Disk Zipped (See Amiga Disk File) | GZip |
| AGDA | Agda (programming language) source file | Agda typechecker/compiler |
| AGR | ArcView ASCII grid | |
| AHK | AutoHotkey script file | AutoHotkey |
| AI | Adobe Illustrator Artwork | Adobe Illustrator |
| AIFF | Audio Interchange File Format | professional audio processing applications and on Macintosh |
| AIFC | Compressed Audio Interchange File Format | |
| AIO | APL programming language file transfer format file | |
| AMF | Additive Manufacturing File Format | Computer Aided Design Software |
| AMG | System image file | ACTOR |
| AML | AutomationML | AutomationML Group |
| AMLX | Compressed and packed AutomationML file | AutomationML Group |
| AMPL | AMPL source code file | AMPL |
| AMR | Adaptive Multi-Rate audio | |
| AMV | Actions Media Video | |
| ANI | Animation cursors for Win | Win95 - WinNT |
| ANN | Annotations of old Windows Help file | Windows 3.0 - XP |
| APE | Monkey's Audio (Lossless) | audio media players |
| APK | Android application package | Android |
| APK | Alpine Linux Package | Alpine Linux and derivatives |
| ARC | ARC (file format) | |
| ART | Gerber format | Cadence Allegro, EAGLE |
| ASAX | ASP.NET global application file | |
| ASCX | ASP.NET User Control | |
| ASF | Advanced Streaming Format (Compressed Windows audio/video) | Microsoft Corporation |
| ASHX | ASP.NET handler file | |
| ASM | Assembler language source | TASM, MASM, NASM, FASM |
| ASPX | Active server page extended file | Microsoft Corporation |
| ASX | Advanced Stream Redirector file, redirects to an ASF file (see ASF) | Microsoft Corporation |
| ATG | Coco/R LL(1) formal grammar | Coco/R |
| AT3 | Atrac 3 Sound/music file | All Sony devices and programs with the Atrac 3+ specification |
| AU | audio file | |
| AVI | Audio Video Interleave | Video for Windows |
| AVIF | AV1 Image File Format | |
| AWK | AWK script/program | awk, GNU Awk, mawk, nawk, MKS AWK, Awka (compiler) |
| AX | DirectShow Filter | Microsoft Corporation (Video Players) |
| AXF | lightweight geodatabase | ESRI ArcPad |

## B

| Ext. | Description | Used by |
| B | BASIC language source | |
| B | bc arbitrary precision calculator language file | Unix bc tool |
| B64 | base64 binary-to-text encoding | |
| BAK | backup | various |
| BAR | Broker Archive. Compressed file containing number of other files for deployment. | IBM App Connect |
| BAS | BASIC language source | QuickBASIC - GW-BASIC - FreeBASIC - others |
| BAT | Batch file | MS-DOS, RT-11, DOS-based command processors |
| BDF | Glyph Bitmap Distribution Format, a format used to store bitmap fonts. | Adobe |
| BDT | Behandlungsdatentransfer, an xDT application | Healthcare providers in Germany |
| BEAM | Executable bytecode file in fat binary format | BEAM (Erlang virtual machine) |
| BIB | Bibliography database | BibTex |
| BIN | binary file | Every OS |
| BLEND | Blender project file | Blender |
| BM3 | UIQ3 Phone backup | |
| BMP | OS/2 or Win graphics format (BitMap Picture) | QPeg - CorelDraw - PC Paintbrush - many |
| BPS | WPS backup file | Microsoft Word, Microsoft Works |
| BSON | JSON-like binary serialization | MongoDB |
| BSP | Binary space partitioning tree file | Quake-based game engines |
| BYU | 3D geometry format | CAD systems |
| BZ2 | Archive | bzip2 |

## C

| Ext. | Description | Used by |
| 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 | |
| CPP | C++ language source | |
| Config | Configuration file | |
| C32 | COMBOOT Executable (32-bit) | SYSLINUX |
| CAB | Cabinet archive | Windows 95 and later, many file archivers |
| CBL | COBOL language source | |
| CBT | COMBOOT Executable (incompatible with DOS COM files) | SYSLINUX |
| CC | C++ language source | |
| CD | ASP.NET class diagram file | |
| CDF | Common Data Format | |
| CDF | Computable Document Format | Mathematica |
| CDP | Trainz Railroad Simulator Content Dispatcher Pack | Trainz Railroad Simulator |
| CDR | Vector graphics format (drawinF | CorelDraw |
| CDXML | MIME type: chemical/x-cdxmlXML version of the ChemDraw Exchange format, CDX. | |
| CER | Security certificate | Microsoft Windows |
| CGM | Computer Graphics Metafile vector graphics | A&L - HG - many |
| CHM | Compiled Help File | Microsoft Windows, Help Explorer Viewer |
| CHO | ChordPro lead sheet (lyrics and chords) | ChordPro and similar tools |
| CIA | Decrypted Nintendo 3DS ROM cartridge | Nintendo 3DS |
| CIF | Crystallographic Information File | RasMol, Jmol |
| CLASS | Java class file | Java |
| CLS | ooRexx class file | ooRexx |
| CMD | Command Prompt batch file | Microsoft Windows NT based operating systems |
| CMD | executable programs | CP/M-86 operating system |
| CML | Chemical Markup Language, for interchange of chemical information. | |
| CMOD | Celestia Model | Celestia |
| CN1 | CNR IDL | MITRE |
| CNOFF | 3D object file format with normals (.noff, .cnoff) NOFF is an acronym derived from Object File Format. Occasionally called CNOFF if color information is present. | |
| COB | COBOL language source | GnuCOBOL |
| COE | Coefficient file | Xilinx ISE |
| COFF | 3D object file format (.off, .coff) OFF is an acronym for Object File Format. Used for storing and exchanging 3D models. Occasionally called COFF if color information is present. | |
| COL | DIMACS graph data format. | |
| COM | DOS program | DOS- |
| COMPILE | ASP.NET precompiled stub file | |
| CPC | Compressed image | Cartesian Perceptual Compression |
| CPIO | cpio archive file | cpio |
| CPL | Control panel file | Windows 3.x |
| CPY | COBOL source copybook file | |
| CR2 | Raw image format | Canon digital cameras |
| CR3 | Raw image format | Canon R series cameras |
| CRAI | CRAM index | |
| CRAFT | Holds Spacecraft Assembly information | Kerbal Space Program |
| CRT | Security certificate | Microsoft Windows |
| CS | C# language source | |
| CSPROJ | C# project file | Microsoft Visual Studio |
| CSS | Cascading style sheet | |
| CSO | Compiled Shader Object, extension of compiled HLSL | High-Level Shading Language |
| CSV | Comma Separated Values text file format (ASCII) | |
| CUB | Used by electronic structure programs to store orbital or density values on a three-dimensional grid. | |
| CUBE | same as .cub | |
| CUR | Non-animated cursor (extended from ICO) | Windows |

## D

| Ext. | Description | Used by |
| D | D Programming Language source file | DMD |
| D | Directory containing configuration files (informal standard) | Unix |
| DAA | Direct Access Archive | |
| DAE | COLLADA file | |
| DAF | Data file | Digital Anchor |
| DART | Dart (programming language) source file | |
| DAT | AMPL data file | AMPL |
| DAT | LDraw (Sub)Part File, 3D Model | LDraw |
| 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 |
| DATS | Dynamic source | ATS |
| DB | Database file | DB Browser for SQLite |
| DBA | DarkBasic source code | |
| DBC | Database Connection configuration file | AbInitio |
| DBF | Native format of the dBASE database management application. | |
| DBG | Debugger script | DOS debug - Watcom debugger |
| DBG | Symbolic debugging information | Microsoft C/C++ |
| DEB | 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. USGSDEM is the standard format for the distribution of terrain elevation data for the United States. |
| DGN | CAD Drawing | Bentley Systems, MicroStation and Intergraph's Interactive Graphics Design System (IGDS) CAD programs |
| DICOM | Digital Imaging and Communications in Medicine (DICOM) bitmap | DICOM Software (XnView) |
| DIF | Data Interchange Format | Visicalc |
| DIF | Output from [diff] command - script for Patch command | |
| DIRED | Directory listing (ls format) | Dired |
| DIVX | DivX media format | |
| DMG | Apple Disk Image | macOS (Disk Utility) |
| DMP | memory dump file (e.g. screen or memory) | |
| DN | Dimension model format | Adobe Dimension |
| DNG | 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 |
| 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 Macro-Enabled Document | Microsoft Word |
| DOCX | Microsoft Word Document | Microsoft Word |
| DOT | Microsoft Word document template | Microsoft Word |
| DOTX | Office Open XML Text document template | Microsoft Word |
| DPX | Digital Picture Exchange | |
| DRC | Dirac format video | |
| DSC | Celestia Deep Space Catalog file | Celestia |
| DTA | Stata database transport format. | Stata |
| DTD | Document Type Definition | |
| DVC | Data version control yaml pointer into blob storage | |
| DWF | Autodesk Design Web Format | Design Review |
| DWG | Drawing | AutoCAD, IntelliCAD, PowerCAD, Drafix, DraftSight etc. |
| DX | same as JDX and JCM. | |
| DXF | Drawing Interchange File Format vector graphics | AutoCAD, IntelliCAD, PowerCAD, etc. |

## E

| Ext. | Description | Used by |
| 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 |
| e57 | 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 |
| EBD | versions of DOS system files (AUTOEXEC.BAT, COMMAND.COM, CONFIG.SYS, WINBOOT.SYS, etc.) for an emergency boot disk | Windows 98, ME |
| EC | Source code | eC |
| ECC | Error-checking file | dvdisaster |
| EDE | Ensoniq EPS disk image | AWAVE |
| EDF | European data format | Medical timeseries storage files |
| EFI | Extensible Firmware Interface | |
| EIS | EIS Spectrum Analyser Project | EIS Spectrum Analyser Archived 2010-03-29 at the Wayback Machine |
| EL | Emacs Lisp source code file | Emacs |
| ELC | Byte-compiled Emacs Lisp code | Emacs |
| ELF | Executable and Linkable File EurekaLog File (contains details of an exception) | Unix EurekaLog (https://www.eurekalog.com/) |
| EMAIL | Outlook Express Email Message | Windows Live Mail, Outlook Express, Microsoft Notepad |
| EMAKER | E language source code (maker) | E |
| EMF | Microsoft Enhanced Metafile | |
| EML | Email conforming to RFC 5322; Stationery Template | Email clients;Outlook Express |
| EMZ | Microsoft Enhanced Metafile compressed with ZIP | Microsoft Office suite |
| EOT | Embedded OpenType | |
| EP | GUI wireframe/prototype project | Prikhi Pencil, Evolus Pencil |
| EPA | Award BIOS splash screen | Award BIOS, XnView |
| EPS | Encapsulated PostScript | CorelDraw - PhotoStyler - PMView - Adobe Illustrator - Ventua Publisher |
| EPUB | 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 |
| ERL | Erlang source code file | |
| ES6 | ECMAScript 6 file | |
| 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 |
| ESD | Windows Imaging Format | ImageX, DISM, 7-Zip, wimlib |
| ETL | event trace log file | Microsoft |
| 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 |
| EX | Elixir source code file | Elixir programming language running on BEAM (Erlang virtual machine) |
| EXE | Directly executable program | DOS, OpenVMS, Microsoft Windows, Symbian or OS/2 |
| EXP | Drawing File format | Drawing Express |
| EXP | 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. | |
| EXS | Elixir script file | Interactive Elixir (IEx) shell |