List of filename extensions (F–L)

|Forth language source code file

|Forth development systems

|Fortran language source code file (in fixed form)

|Many Fortran compilers

|Fax

|perfectfax

|Fortran language source code file (in free form)

|Many Fortran compilers

|Fortran language source code file (in free form)

|Fortran compilers

|Fortran language source code file (in free form)

|Fortran compilers

|Fortran IV source code file

|Fortran IV source code

|A container format for Flash Video that differs from the older FLV file format (see also SWF)

|Adobe Flash

|Fortran language source code file (in fixed form)

|Many Fortran compilers

|Fortran language source code file (in free form)

|Many Fortran compilers

|Fortran language source code file (in free form)

|Many Fortran compilers

| Factor source file

|

|Forth language block file

|Forth development systems

| FictionBook e-book 2.0 file (DRM-free XML format)

|e-book readers

|3D model geometry, material textures, lighting, armature, and animation sequences for inter application use/transport

|Autodesk

|Gaussian-formatted checkpoint file. Used to store result of quantum chemistry calculation results.{{Cite web |title=FCHK (.fchk) |url=https://reference.wolfram.com/language/ref/format/FCHK.html}}

|

|FCS molecular biology format.{{Cite web |title=FCS (.fcs, .lmd) |url=https://reference.wolfram.com/language/ref/format/FCS.html}}

|

|Forsyth–Edwards Notation

| Chess applications -text data describes a specific position.

|[https://tools.suckless.org/farbfeld/ Farbfeld] image

|

|FrontFace plugin file

|[https://www.mirabyte.com/en/frontface/ FrontFace] digital signage software

|CurvFit Input file format

|[https://goal-driven.net/apps/curvfit.html CurvFit] software

|Flexible Image Transport System

|astronomy software

|Fractal configuration file

|Apophysis

|FL Studio project file

|FL Studio

|A container format for Flash Video (see also SWF)

|Adobe Flash

|A Functional Mockup Unit (FMU) implements the Functional Mockup Interface (FMI).{{Cite web |title=FMU (.fmu) |url=https://reference.wolfram.com/language/ref/format/FMU.html}}

|

|FileNet Native Document

|FileNet

|Saved notes with formatting in markup language

|FeatherNote

|OpenDocument Flat XML Drawings and vector graphics

|OpenDocument, LibreOffice, Collabora Online

|Fortran language source file

|many

|Match-n-Freq (TM) Input file format

|[https://goal-driven.net/apps/match-n-freq.html Match-n-Freq] software

|Fragment File, usually stored on MOVPKG files

|MOVPKG

|MySQL Database Metadata

|MySQL

|Match-n-Freq (TM) version 7+ Input file format

|[https://goal-driven.net/apps/match-n-freq.html Match-n-Freq] software

|F# source file

|F# compilers

|Forth language source code file (often used to distinguish from .fb)

|Forth development systems

|Forth language source code file

|Forth development systems

|ANTLR4 grammar

| ANTLR4

|Graph6 graph data format. Used for storing undirected graphs.{{Cite web |title=Graph6 (.g6) |url=https://reference.wolfram.com/language/ref/format/Graph6.html}}

|

|GenBank molecular biology format.{{Cite web |title=GenBank (.gb, .gbk) |url=https://reference.wolfram.com/language/ref/format/GenBank.html}}

|

|same as GB

|

|Gerber format

| PCB CAD/CAM

|General Data Format for Biomedical Signals

|Biomedical signal processing, Brain Computer Interfaces

|Godot (game engine) Script File

|Godot (game engine)

|Gerätedatentransfer, an xDT application

|Healthcare providers in Germany

|GEDCOM

|Genealogy data exchange

|GeoJSON is specified by RFC 7946.{{Cite web |title=GeoJSON (.geojson) |url=https://reference.wolfram.com/language/ref/format/GeoJSON.html}}

|

|Used for archiving and exchanging aerial photography or terrain data.{{Cite web |title=GeoTIFF (.tif, .tiff) |url=https://reference.wolfram.com/language/ref/format/GeoTIFF.html}}

|

|GeoGebra File

|GeoGebra

|Compuserves' Graphics Interchange Format (bitmapped graphics)

|QPeg - Display - CompuShow

|Scripts for GodMode9

|Godmode9

|Gemtext markup language{{Cite web|title=Project Gemini|url=https://gemini.circumlunar.space/docs/specification.gmi|access-date=2021-11-24|website=gemini.circumlunar.space}}

|Gemini (Protocol)

|GameMaker Project File

|YoYo Games

|Geography Markup Language File

|Geography Markup Language

|Used for the storage and exchange of graphs. Native format of the Graphlet graph editor software.{{Cite web |title=Graphlet (.gml) |url=https://reference.wolfram.com/language/ref/format/Graphlet.html}}

|

|Go source code file

|Go (Programming language)

|Godot (game engine) Project File

|Godot (game engine)

|GPS eXchange Format

|

|GraphML is an acronym derived from Graph Markup Language. Represents typed, attributed, directed, and undirected graphs.{{Cite web |title=GraphML (.graphml) |url=https://reference.wolfram.com/language/ref/format/GraphML.html}}

|

|Commonly used in meteorology to store historical and forecast weather data. Represents numerical weather prediction output (NWP).{{Cite web |title=GRIB (.grb, .grib) |url=https://reference.wolfram.com/language/ref/format/GRIB.html}}

|

|Uncompressed folder as a file

|WinGrex/GrexliLib

|same as GRB

|

|Data pack files for the Build Engine

|Duke Nukem 3D

|Generic sensor format

|Used for storing bathymetry data, such as that gathered by a multibeam echosounder.

|Gene transfer format

|

|Graph Visualization

|Graphviz

|same as .lgr. See LGR below for details on LEDA (.gw, .lgr).

|

|GXL is an acronym derived from Graph Exchange Language. Represents typed, attributed, directed, and undirected graphs.{{Cite web |title=GXL (.gxl) |url=https://reference.wolfram.com/language/ref/format/GXL.html}}

|

|gzip compressed data

|gzip

|On-line help file

|Flambeaux Help! Display Engine

|Pertext database

|HELP.EXE

|C-- language header

|Sphinx C--

|Header file (usually C language)

|Watcom C/C++

|Header file

|C++

|Archive

|HA

|Source file for the programming language hack

|The HHVM{{cite web |title=HHVM 4.0.0 |url=http://hhvm.com/blog/2019/02/11/hhvm-4.0.0.html |website=HHVM}}

|HTTP Archive format (JSON-format web-browser log)

|W3C draft standard

|General-purpose format for representing multidimensional datasets. Developed by the US National Center for Supercomputing Applications (NCSA).{{Cite web |title=HDF (.hdf) |url=https://reference.wolfram.com/language/ref/format/HDF.html}}

|

|General-purpose format for representing multidimensional datasets and images. Incompatible with HDF Version 4 and earlier.{{Cite web |title=HDF5 (.h5, .hdf5) |url=https://reference.wolfram.com/language/ref/format/HDF5.html}}

|

|Hard Disk Image file (PC-9800 disk image file)

|PC-9800 emulators

|heap dumpfile

|

|HEIF raster image and compression format. Commonly used for storing still or animated images.{{Cite web |title=HEIF (.heic, .heif) |url=https://reference.wolfram.com/language/ref/format/HEIF.html}}

|

|same as HEIC.

|

|C++ header file

|

|HyperChem HIN format. Used in cheminformatics applications and on the web for storing and exchanging 3D molecule models. Maintained by HyperCube, Inc.{{Cite web |title=HIN (.hin) |url=https://reference.wolfram.com/language/ref/format/HIN.html}}

|

|Basic Configuration file

|OMSI The Bus Simulator

|Hearts Of Iron 4 file

|Hearts Of Iron 4 Save game

|C++ header file

|Zortech C++ - Watcom C/C++

|HTML Application

|Microsoft Windows

|see HTML

|

|Hypertext Markup Language (WWW)

|Netscape - Mosaic - many

|3D Model database

|OMSI The Bus Simulator

|C++ header file

|

|same as ICS (see below).

|

|ICC profile

|Color Configuration for color input or output devices

|LHA Archive

|Cracked LHA (old LHA), Total Commander

|Icon library

|Microsoft Windows

|Macintosh icons format. Raster image file format.{{Cite web |title=ICNS (.icns) |url=https://reference.wolfram.com/language/ref/format/ICNS.html}}

|

|Icon file

|ICONEDIT.EXE; Microsoft Windows

|ICS iCalendar format. Used for the storage and exchange of calendar information. Commonly used in personal information management systems.{{Cite web |title=ICS (.ics, .ical, .ifb) |url=https://reference.wolfram.com/language/ref/format/ICS.html}}

|

|Same as ICS (see above).

|

|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

|Flight tracks downloaded from GPS devices in the International Gliding Commission's prescribed format

|

|Initial Graphics Exchange Specification

|

|Disk image

|

|Texinfo hypertext document

|Texinfo, info (Unix), Emacs

|Configuration file

|

|Archive

|CPIO

|XnView IPTC template

|XnView, XnViewMP

|AIX iptrace captures{{Cite web |title=5.2. Open Capture Files |url=https://www.wireshark.org/docs/wsug_html_chunked/ChIOOpenSection.html}} dualhome.iptrace (AIX iptrace) Shows Ethernet and Token Ring packets captured in the same file.{{Cite web |title=SampleCaptures |url=https://wiki.wireshark.org/SampleCaptures}}

|WireShark

|Main file for programming a VEX Robot

|VEX Robotics

|"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-9660 table

|see: List of ISO image software

|Impulse Tracker music file

|Impulse Tracker

| Julia script file

|Julia (programming language)

|JPEG 2000 image

|JPEG 2000

|JPEG2000 raster image and compression format. Can store images as an array of rectangular tiles that are encoded separately.{{Cite web |title=JPEG2000 (.jp2, .j2k) |url=https://reference.wolfram.com/language/ref/format/JPEG2000.html}}

|

|Java archive

|JAR, Java Games and Applications

|Java source code file

|

|Joint Bilevel Image Group

|

|same as JDX (see below).

|

|Chemical spectroscopy format. JCAMP is an acronym derived from Joint Committee on Atomic and Molecular Physical Data.{{Cite web |title=JCAMP-DX (.jdx, .dx, .jcm) |url=https://reference.wolfram.com/language/ref/format/JCAMP-DX.html}}

|

|Java Network Launching Protocol

|Java Web Start

|Joint Photographic Experts Group graphics file format

|QPeg - FullView - Display

|JavaScript file

|script in HTML pages

|JSON (JavaScript Object Notation)

|Ajax

|Jakarta Server Pages

|Dynamic pages running Web servers using Java technology

|Beyond Jump save file

|Cell to Singularity

|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.{{Cite web |title=JVX (.jvx) |url=https://reference.wolfram.com/language/ref/format/JVX.html}}

|

|JPEG XL raster graphics file

|Keynote Presentation

|Keynote

|MSKLC Source file

|Microsoft Keyboard Layout Creator

|Keyhole Markup Language

|Google Earth

| Linux kernel module format system file

| Linux

| Krita image file

|Krita

| Kraber source code file

|[https://github.com/intfract/kraber Kraber Programming Language]

| Kornshell source file

| Kornshell

|Kotlin source code file

|Kotlin Programming Language

|Kivy

|

|Dymo label file

|Dymo desktop software

|LaTeX typesetting system and programming language. Commonly used for typesetting mathematical and scientific publications.{{Cite web |title=LaTeX (.tex) |url=https://reference.wolfram.com/language/ref/format/LaTeX.html}}{{Cite web |title=Listing of All Formats |url=https://reference.wolfram.com/language/guide/ListingOfAllFormats.html}}

|

|.LBR Archive

|for CP/M and MS-DOS using the LU program

|.LDB Leveldb data file

|Google key-value storage library

|.LDB MDB Database lock file

|Microsoft Access Database

|Labordatenträger, an xDT application

|Healthcare providers in Germany

|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.{{Cite web |title=LEDA (.gw, .lgr) |url=https://reference.wolfram.com/language/ref/format/LEDA.html}}

|

|LHA Archive

|LHA/LHARC, Total Commander

|LISP source code file

|

|LLVM Assembly Language

|llvm

|Language Model File{{cite web |title=LM file - What is an LM file and how do I open it? |url=https://fileinfo.com/extension/lm |website=fileinfo.com |access-date=12 August 2023}}

|Microsoft Windows

|FCS molecular biology format.

|

|Local file shortcut

|Microsoft Windows

|Logic Pro files

|Logic Pro (MacOS, iPadOS)

|Lyrics file

|Lyrics for karaoke-related system and program

|Lua script file

|Lua (programming language)

|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.{{Cite web |title=LWO (.lwo) |url=https://reference.wolfram.com/language/ref/format/LWO.html}}

|

|Archive

|Lzip