# List of filename extensions (F–L)

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

## F

| Ext. | Description | Used by |
| 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 |
| F08 | Fortran language source code file (in free form) | Fortran compilers |
| F18 | Fortran language source code file (in free form) | Fortran compilers |
| F4 | Fortran IV source code file | Fortran IV source code |
| 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 |
| FA | FASTA format sequence file | |
| FAA | FASTA format amino acid | |
| FACTOR | Factor source file | |
| FASTA | FASTA format sequence file | |
| FASTQ | FASTQ format sequence file | |
| FB | Forth language block file | Forth development systems |
| FB2 | FictionBook e-book 2.0 file (DRM-free XML format) | e-book readers |
| FBX | 3D model geometry, material textures, lighting, armature, and animation sequences for inter application use/transport | Autodesk |
| FCHK | Gaussian-formatted checkpoint file. Used to store result of quantum chemistry calculation results. | |
| FCS | FCS molecular biology format. | |
| FEN | Forsyth–Edwards Notation | Chess applications -text data describes a specific position. |
| FF | Farbfeld image | |
| FFAPX | FrontFace plugin file | FrontFace digital signage software |
| FFN | FASTA format nucleotide of gene regions | |
| Fit | CurvFit Input file format | CurvFit software |
| FITS | Flexible Image Transport System | astronomy software |
| FLAC | Audio codec, Audio file format | |
| FLAME | Fractal configuration file | Apophysis |
| FLP | FL Studio project file | FL Studio |
| FLV | A container format for Flash Video (see also SWF) | Adobe Flash |
| FMU | A Functional Mockup Unit (FMU) implements the Functional Mockup Interface (FMI). | |
| FNA | FASTA format nucleic acid | |
| FNI | FileNet Native Document | FileNet |
| FNX | Saved notes with formatting in markup language | FeatherNote |
| FODG | OpenDocument Flat XML Drawings and vector graphics | OpenDocument, LibreOffice, Collabora Online |
| FODP | OpenDocument Flat XML Presentations | OpenDocument, LibreOffice, Collabora Online |
| FODS | OpenDocument Flat XML Spreadsheets | OpenDocument, LibreOffice, Collabora Online |
| FODT | OpenDocument Flat XML Text Document | OpenDocument, LibreOffice, Collabora Online |
| FOR | Fortran language source file | many |
| FQL | Fauna Query Language source file | Fauna |
| Freq | Match-n-Freq (TM) Input file format | Match-n-Freq software |
| FRAG | Fragment File, usually stored on MOVPKG files | MOVPKG |
| FRM | MySQL Database Metadata | MySQL |
| Frq7 | Match-n-Freq (TM) version 7+ Input file format | Match-n-Freq software |
| FS | F# source file | F# compilers |
| FS | Forth language source code file (often used to distinguish from .fb) | Forth development systems |
| FTH | Forth language source code file | Forth development systems |

## G

| Ext. | Description | Used by |
| G4 | ANTLR4 grammar | ANTLR4 |
| G6 | Graph6 graph data format. Used for storing undirected graphs. | |
| GB | GenBank molecular biology format. | |
| GBK | same as GB | |
| GBR | Gerber format | PCB CAD/CAM |
| GDF | General Data Format for Biomedical Signals | Biomedical signal processing, Brain Computer Interfaces |
| GDSCRIPT | Godot (game engine) Script File | Godot (game engine) |
| GDT | Gerätedatentransfer, an xDT application | Healthcare providers in Germany |
| GED | GEDCOM | Genealogy data exchange |
| GEOJSON | GeoJSON is specified by RFC 7946. | |
| GEOTIFF | Used for archiving and exchanging aerial photography or terrain data. | |
| GGB | GeoGebra File | GeoGebra |
| GIF | Compuserves' Graphics Interchange Format (bitmapped graphics) | QPeg - Display - CompuShow |
| GM9 | Scripts for GodMode9 | Godmode9 |
| GMI | Gemtext markup language | Gemini (Protocol) |
| GMK | GameMaker Project File | YoYo Games |
| GML | Geography Markup Language File | Geography Markup Language |
| GML | Used for the storage and exchange of graphs. Native format of the Graphlet graph editor software. | |
| GO | Go source code file | Go (Programming language) |
| GODOT | Godot (game engine) Project File | Godot (game engine) |
| GPX | GPS eXchange Format | |
| GRAPHML | GraphML is an acronym derived from Graph Markup Language. Represents typed, attributed, directed, and undirected graphs. | |
| GRB | Commonly used in meteorology to store historical and forecast weather data. Represents numerical weather prediction output (NWP). | |
| GREXLI | Uncompressed folder as a file | WinGrex/GrexliLib |
| GRIB | same as GRB | |
| GRP | Data pack files for the Build Engine | Duke Nukem 3D |
| GSF | Generic sensor format | Used for storing bathymetry data, such as that gathered by a multibeam echosounder. |
| GTF | Gene transfer format | |
| GV | Graph Visualization | Graphviz |
| GW | same as .lgr. See LGR below for details on LEDA (.gw, .lgr). | |
| GXL | GXL is an acronym derived from Graph Exchange Language. Represents typed, attributed, directed, and undirected graphs. | |
| GZ | gzip compressed data | gzip |

## H

| Ext. | Description | Used by |
| 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 |
| HACK | Source file for the programming language hack | The HHVM |
| HAR | HTTP Archive format (JSON-format web-browser log) | W3C draft standard |
| HDF | General-purpose format for representing multidimensional datasets. Developed by the US National Center for Supercomputing Applications (NCSA). | |
| HDF5 | General-purpose format for representing multidimensional datasets and images. Incompatible with HDF Version 4 and earlier. | |
| HDI | Hard Disk Image file (PC-9800 disk image file) | PC-9800 emulators |
| HDMP | heap dumpfile | |
| HEIC | HEIF raster image and compression format. Commonly used for storing still or animated images. | |
| HEIF | same as HEIC. | |
| HH | C++ header file | |
| HIN | HyperChem HIN format. Used in cheminformatics applications and on the web for storing and exchanging 3D molecule models. Maintained by HyperCube, Inc. | |
| HOF | Basic Configuration file | OMSI The Bus Simulator |
| HOI4 | Hearts Of Iron 4 file | Hearts Of Iron 4 Save game |
| HPP | C++ header file | Zortech C++ - Watcom C/C++ |
| HTA | HTML Application | Microsoft Windows |
| HTM | see HTML | |
| HTML | Hypertext Markup Language (WWW) | Netscape - Mosaic - many |
| HUM | 3D Model database | OMSI The Bus Simulator |
| HXX | C++ header file | |

## I

| Ext. | Description | Used by |
| ICAL | same as ICS (see below). | |
| ICC | ICC profile | Color Configuration for color input or output devices |
| ICE | LHA Archive | Cracked LHA (old LHA), Total Commander |
| ICL | Icon library | Microsoft Windows |
| ICNS | Macintosh icons format. Raster image file format. | |
| ICO | Icon file | ICONEDIT.EXE; Microsoft Windows |
| ICS | ICS iCalendar format. Used for the storage and exchange of calendar information. Commonly used in personal information management systems. | |
| IFB | Same as ICS (see above). | |
| IFC | Industry Foundation Classes (platform neutral, open file format used by BIM software). It is registered by ISO and is an official International Standard ISO 16739-1:2018. | BIM software |
| IGC | Flight tracks downloaded from GPS devices in the International Gliding Commission's prescribed format | |
| IGES | Initial Graphics Exchange Specification | |
| IMG | Disk image | |
| INFO | Texinfo hypertext document | Texinfo, info (Unix), Emacs |
| INI | Configuration file | |
| IO | Archive | CPIO |
| IPT | XnView IPTC template | XnView, XnViewMP |
| IPTRACE | AIX iptrace captures dualhome.iptrace (AIX iptrace) Shows Ethernet and Token Ring packets captured in the same file. | WireShark |
| IQBLOCKS | Main file for programming a VEX Robot | VEX Robotics |
| IRX | "IOP Relocatable eXecutable". Library files to dynamically link application code to the Input/Output Processor on the PS2 to communicate with devices like memory cards, USB devices, etc. | Sony PlayStation 2 |
| ISO | ISO-9660 table | see: List of ISO image software |
| IT | Impulse Tracker music file | Impulse Tracker |

## J

| Ext. | Description | Used by |
| JL | Julia script file | Julia (programming language) |
| J2C | JPEG 2000 image | JPEG 2000 |
| J2K | JPEG2000 raster image and compression format. Can store images as an array of rectangular tiles that are encoded separately. | |
| JAR | Java archive | JAR, Java Games and Applications |
| JAV | see JAVA | |
| JAVA | Java source code file | |
| JBIG | Joint Bilevel Image Group | |
| JCM | same as JDX (see below). | |
| JDX | Chemical spectroscopy format. JCAMP is an acronym derived from Joint Committee on Atomic and Molecular Physical Data. | |
| JNLP | Java Network Launching Protocol | Java Web Start |
| JP2 | JPEG 2000 image | |
| JPE | Joint Photographic Experts Group graphics file format | Minolta/Konica Minolta cameras use this for JPEGs in Adobe RGB color space |
| JPEG | Joint Photographic Experts Group graphics file format | QPeg - FullView - Display |
| JPG | Joint Photographic Group | various (Minolta/Konica Minolta cameras use this for JPEGs in sRGB color space) |
| JS | JavaScript file | script in HTML pages |
| JSON | JSON (JavaScript Object Notation) | Ajax |
| JSP | Jakarta Server Pages | Dynamic pages running Web servers using Java technology |
| JUMP | Beyond Jump save file | Cell to Singularity |
| JVX | JavaView 3D geometry format. The native format of the JavaView visualization software. Used for the visualization of 2D or 3D geometries. Can be embedded in web pages and viewed with the JavaView applet. | |
| JXL | JPEG XL raster graphics file |

## K

| Ext. | Description | Used by |
| KEY | Keynote Presentation | Keynote |
| KLC | MSKLC Source file | Microsoft Keyboard Layout Creator |
| KML | Keyhole Markup Language | Google Earth |
| KMZ | Keyhole Markup Language (Zip compressed) | Google Earth |
| KO | Linux kernel module format system file | Linux |
| KRA | Krita image file | Krita |
| KRABER | Kraber source code file | Kraber Programming Language |
| KSH | Kornshell source file | Kornshell |
| KT | Kotlin source code file | Kotlin Programming Language |
| KV | Kivy | |

## L

| Ext. | Description | Used by |
| LABEL | Dymo label file | Dymo desktop software |
| LATEX | LaTeX typesetting system and programming language. Commonly used for typesetting mathematical and scientific publications. | |
| LBR | .LBR Archive | for CP/M and MS-DOS using the LU program |
| LDB | .LDB Leveldb data file | Google key-value storage library |
| LDB | .LDB MDB Database lock file | Microsoft Access Database |
| LDT | Labordatenträger, an xDT application | Healthcare providers in Germany |
| LGR | LEDA graph data format. Commonly used exchange format for graphs. Stores a single, typed, directed, or undirected graph. Native graph file format of the LEDA graph library and the GraphWin application. LEDA is an acronym for Library of Efficient Datatypes and Algorithms. | |
| LHA | LHA Archive | LHA/LHARC, Total Commander |
| LISP | LISP source code file | |
| LL | LLVM Assembly Language | llvm |
| LM | Language Model File | Microsoft Windows |
| LMD | FCS molecular biology format. | |
| LNK | Local file shortcut | Microsoft Windows |
| LOGICX | Logic Pro files | Logic Pro (MacOS, iPadOS) |
| LRC | Lyrics file | Lyrics for karaoke-related system and program |
| LUA | Lua script file | Lua (programming language) |
| LWO | Native format of the LightWave 3D rendering and animation software. LWO is an acronym for LightWave Object. Developed by NewTek. Stores 3D objects as a collection of polygons and their properties. | |
| LZ | Archive | Lzip |