| File extension | Developer/Producer | File description |
|---|---|---|
| J file extension | Oracle | Java Source Code |
| J2B file extension | Epic Games, Inc. | Jazz Jackrabbit 2 Music |
| J2C file extension | Joint Photographic Experts Group | JPEG2000 Image Format |
| J2D file extension | Epic Games, Inc. | Jazz Jackrabbit Data |
| J2E file extension | Epic Games, Inc. | Jazz Jackrabbit 2 Episode |
| J2I file extension | Epic Games | Jazz Jackrabbit 2 Internet Server Link Format |
| J2K file extension | Joint Photographic Experts Group | JPEG2000 Code Stream Image |
| J2L file extension | Epic Games | Jazz Jackrabbit 2 Level Format |
| J2SI file extension | Epic Games, Inc. | Jazz Jackrabbit 2 Internet Server Link |
| J2W file extension | Esri | ArcExplorer World |
| J3O file extension | jMonkeyEngine | JMonkeyEngine 3D Scene |
| J6I file extension | N/A | Ricoh Digital Camera Image |
| JA file extension | N3V Games | Jet Archive |
| JAC file extension | Kai Kretschmann | JaStaCry Encrypted Format |
| JACL file extension | IBM | IBM WebSphere Server Script |
| JAD file extension | Sun Microsystems | Java Application Descriptor Format |
| JADE file extension | N/A | Jade Programming Language Source Code |
| JAG file extension | Jagex | Jagex Data Format |
| JAI file extension | JThink Ltd | Jaikoz Settings |
| JAM file extension | Sony | PS3 Unreal Tournament 3 Mod Format |
| JAN file extension | Janome Sewing Machine Co., Ltd. | Janome Digitizer Embroidery Object |
| JAP file extension | N/A | Japanese Nintendo 64 Game ROM |
| JAR file extension | Oracle | Compressed Archive Format Package For Java Classes And Data Format |
| JARPACK file extension | Oracle | Oracle Pack200 Packed JAR Format |
| JARDESC file extension | The Eclipse Foundation | Eclipse JAR Settings |
| JARVIS file extension | Jarvis Acting Company | Jarvis Subscriber Format |
| JAS file extension | Cheetah3D | Cheetah3D Model Format |
| JASPER file extension | Jaspersoft | JasperReports Data Format |
| JAV file extension | Oracle | Java Language Source Code Format |
| JAVA file extension | Oracle | Java Language Source Code Format |
| JAVAJET file extension | The Eclipse Foundation | Eclipse JET Java Template |
| JAX file extension | Oracle Corporation | Java Executable JAR |
| JB2 file extension | Joint Bi-level Image Group | JBIG2 Image Format |
| JBC file extension | Altera | Jam STAPL Byte-Code Format |
| JBF file extension | Corel | Corel PaintShop Photo Pro Image Browser Format |
| JBG file extension | N/A | Image JBIG 1-bit Raster |
| JBI file extension | Motoman | Motoman Robot Job Format |
| JBIG file extension | Joint Bi-level Image Group | JBIG Raster Image Graphics |
| JBIG2 file extension | Joint Bi-level Image Group | JBIG2 |
| JBK file extension | N/A | Juno Backup Format |
| JBL file extension | id Software LLC | Doom Scene Add-on |
| JBMP file extension | JAmes OS | JAmes OS Bitmap Image |
| JBR file extension | Corel | Corel PaintShop Photo Pro Brushes Format |
| JBT file extension | Freedom Scientific, Inc. | JAWS |
| JC file extension | FlashGet | FlashGet Partial Download Format |
| JC! file extension | FlashGet | FlashGet Incomplete Download Format |
| JCC file extension | New Planet Software | Code Crusader Project Data |
| JCCFG3 file extension | Trend Media Corporation Limited | FlashGet Incomplete Download |
| JCD file extension | Trend Media Corporation Limited | FlashGet Saved |
| JCF file extension | Freedom Scientific, Inc. | JAWS Configuration |
| JCLIC file extension | JClic | JClic Project Format |
| JCM file extension | Oracle Corporation | Java Commerce Message |
| JCP file extension | Xinox Software | JCreator Project Format |
| JCRYPT file extension | JMasters | JCRYPT Encrypted Format |
| JCS file extension | Oracle Corporation | Java Control Source |
| JCSK file extension | JetAudio Inc. | JetCast Skin |
| JCT file extension | SourceForge.net | JCT |
| JCZ file extension | Microsoft | Microsoft Liquid Motion Animation Format |
| JDB file extension | Symantec | Norton Antivirus Definiton Update File Format |
| JDC file extension | The JDownloader Team | JDownloader Links Format |
| JDF file extension | Adobe Systems | Adobe Acrobat Job Definition Format |
| JDP file extension | BlackBerry (Research In Motion Limited) | BlackBerry JDE |
| JDW file extension | BlackBerry (Research In Motion Limited) | BlackBerry JDE |
| JDX file extension | Page Scholar Inc. | JSpell Dictionary |
| JEB file extension | N/A | PENSIM Output |
| JED file extension | N/A | Xilinx Integrated Software Environment Device Configuration Information Format |
| JEF file extension | Janome | Janome Embroidery Layout Format |
| JETINC file extension | The Eclipse Foundation | Eclipse IDE Template Fragment |
| JEWELQUESTSAVEDGAME file extension | iWin, Inc. | Jewel Quest Saved Game |
| JFD file extension | Freedom Scientific, Inc. | JAWS Synopsis |
| JFF file extension | Freedom Scientific, Inc. | JAWS Ini |
| JFFS2 file extension | Various Linux developers | Journalling Flash File System 2 Disk Image |
| JFI file extension | Joint Photographic Experts Group | JPEG File Interchange Format |
| JFIF file extension | N/A | JPEG Interchange Format |
| JFL file extension | Systat Software Inc. | SigmaPlot |
| JFR file extension | Renato Nobili | WJVN Fragment |
| JFS file extension | N/A | Linux/Unix Journaling System |
| JFX file extension | N/A | J2 Fax |
| JG4 file extension | Lena Games | BigJig Jigsaw Puzzle Format |
| JGCSCS file extension | Just Great Software | EditPad Syntax Scheme |
| JGD file extension | Corel Corporation | Corel PaintShop Photo Pro Gradients |
| JGF file extension | Freedom Scientific, Inc. | JAWS Ini |
| JGP file extension | Jolly Giant Software Inc. | QWS3270 PLUS Session Parameter |
| JGS file extension | Jolly Giant Software Inc. | QWS3270 PLUS Script |
| JGW file extension | ESRI | JPEG World Format |
| JGZ file extension | N/A | Gzipped JavaScript Format |
| JHM file extension | Oracle Corporation | Java Help Mapping |
| JHTML file extension | N/A | ATG Dynamo Server Page (Java HTML) |
| JIA file extension | JVC | Digital Photo Navigator Album |
| JIC file extension | N/A | Java Icon Format |
| JIF file extension | N/A | JPEG Interchange Format |
| JIFF file extension | N/A | JPG Bitmap Image |
| JIG file extension | GameHouse, Inc. | GameHouse Puzzle Jigsaw Game |
| JIGSAW file extension | Carolina Road Software | Jigsaw Explorer Puzzle Format |
| JIGZ file extension | Bitz & Pixelz BV | Jiggsaw Puzzle |
| JIS file extension | N/A | Japanese Industry Standard Text Format |
| JISP file extension | N/A | Tkabber Emoticon Set |
| JIT file extension | Gala-Net Inc. | Aika Online Texture |
| JJ file extension | N/A | Doodle C64 Compressed Image Format |
| JJF file extension | Flash Jester | Flash Jester Jugglor |
| JJJS file extension | Apple, Inc. | Claris Organizer Format |
| JKB file extension | id Software LLC | Quake 3 Arena Bot AI |
| JKL file extension | LucasArts Entertainment Company, LLC | Jedi Knight |
| JKM file extension | Freedom Scientific | JAWS Ini Configuration Format |
| JKS file extension | LucasArts Entertainment Company, LLC | Jedi Knight Save |
| JL file extension | Julia | Julia Source Code Format |
| JLB file extension | N/A | PAC Mate BX Keyboard Driver |
| JLC file extension | N/A | Byte Compiled Lisp-based Script |
| JLS file extension | Freedom Scientific, Inc. | JAWS |
| JMA file extension | N/A | NSRT Compressed Game |
| JMD file extension | Corel Corporation | Corel PaintShop Pro Image Map Settings |
| JMF file extension | Oracle Corporation | Java Media Framework |
| JML file extension | N/A | Java Modeling Language Specification |
| JMP file extension | SAS Institute | SAS JMP Discovery Chart-to-statistics |
| JMS file extension | Voxtron N.V. | Voxtron TeleButler Interactive Voice Response Call Flow |
| JMV file extension | Jabsoft | Jnes Record Format |
| JMX file extension | Apache Software Foundation | Apache JMeter |
| JNB file extension | Systat Software Inc. | SigmaPlot Workbook |
| JNG file extension | N/A | JPEG Network Graphic Format |
| JNILIB file extension | Oracle | Mac OS X Java JNI Library Format |
| JNL file extension | Actian Corporation | Ingres Journal |
| JNLP file extension | N/A | Java Network Launching Protocol Format |
| JNT file extension | Microsoft | Microsoft Windows Journal Note Format |
| JNX file extension | N/A | Garmin Raster Map |
| JO file extension | Abadie-jo | Jo Audio Format |
| JO-7Z file extension | Abadie-jo | Jo Audio Format |
| JOB file extension | Microsoft | Microsoft Windows Task Scheduler Task Object Format |
| JOBOPTIONS file extension | Adobe Systems | Adobe Acrobat Job Options Format |
| JOBS file extension | Avery Lee | VirtualDub Job |
| JOD file extension | Microsoft Corporation | Microsoft Jet OLEDB.4.0 |
| JOE file extension | Cyril Hicks | .joe Editor Document Format |
| JOINED file extension | Freebyte | HJSplit Data Format |
| JOML file extension | Microsoft Corporation | JOOB Object Modelling Language |
| JOMPROJ file extension | Microsoft Corporation | Microsoft Visual Studio JOOB Object Model Project |
| JOR file extension | Microsoft Corporation | Microsoft SQL Server Journal |
| JOT file extension | King Stairs Software | Jot+ Notes Note Data |
| JOURNALDOC file extension | SolidWorks Corporation | SolidWorks Design Journal Template |
| JOURNAL_INFO_BLOCK file extension | Apple, Inc. | Apple Mac OS Xsystem |
| JOY file extension | Crytek | CryENGINE Facial Editor Joystick Settings Format |
| JP1 file extension | N/A | Japanese (Romaji) Text Format |
| JP2 file extension | Joint Photographic Experts Group | JPEG 2000 Image Format (ISO 15444-1) Format |
| JP3 file extension | Electric Quilt | Electric Quilt |
| JP4 file extension | Electric Quilt | Electric Quilt |
| JP5 file extension | Electric Quilt | Electric Quilt |
| JPA file extension | N/A | Joomla Installation Backup |
| JPAGE file extension | The Eclipse Foundation | Eclipse Java Scrapbook Page |
| JPB file extension | JSoftware | Publish Manager Report |
| JPC file extension | Joint Photographic Experts Group | JPEG2000 Code Stream Image Format |
| JPD file extension | N/A | Joint PhotoDefiner Image Format |
| JPE file extension | Joint Photographic Experts Group | JPEG Bitmap Image Format |
| JPEG file extension | Joint Photographic Experts Group | JPEG Bitmap Image Format |
| JPEGENX file extension | Egis Technology Inc. | Egis Encrypted JPEG |
| JPEG_160X120 file extension | N/A | 160 X 120 Pixels JPEG Image |
| JPEG_170X220 file extension | N/A | 170 X 220 Pixels JPEG Image |
| JPF file extension | Joint Photographic Experts Group | JPEG 2000 Extended Image Format (ISO 15444-2) Format |
| JPG file extension | Joint Photographic Experts Group | JPEG Bitmap Image Format |
| JPG2 file extension | Joint Photographic Experts Group | JPEG 2000 Image Format (ISO 15444-1) Format |
| JPGENX file extension | Egis Technology Inc. | Egis Encrypted JPG |
| JPGW file extension | ESRI | JPEG World Format |
| JPGX file extension | Egis Technology Inc. | Egis Encrypted JPG Bitmap Image |
| JPG_108X192 file extension | N/A | Android Picture |
| JPG_128X128 file extension | N/A | Android Picture |
| JPG_128X160 file extension | N/A | Android Picture |
| JPG_128X96 file extension | N/A | Android Picture |
| JPG_160X120 file extension | N/A | Android Picture |
| JPG_160X128 file extension | N/A | Android Picture |
| JPG_170X128 file extension | N/A | Android Picture |
| JPG_170X220 file extension | N/A | Android Picture |
| JPG_220X176 file extension | N/A | Android Picture |
| JPG_240X320 file extension | Google Inc. | Android Picture |
| JPG_320X240 file extension | N/A | Android Picture |
| JPG_320X320 file extension | N/A | Android Picture |
| JPG_480X320 file extension | N/A | Android Picture |
| JPG_512X512 file extension | Google Inc. | Android Picture |
| JPG_56X42 file extension | N/A | Android Picture |
| JPG_T file extension | N/A | JPEG Image |
| JPH file extension | Quest | JProbe Memory Snapshot Format |
| JPI file extension | Elfin Sp. z o.o. | Jupiter Encrypted XML |
| JPL file extension | Quest Software, Inc. | JProbe Settings |
| JPM file extension | N/A | JPEG 2000 Multi-layer Image Format (ISO 15444-6) |
| JPN file extension | Microsoft | Windows Japanese Noise-Word List Format |
| JPP file extension | N/A | Jigsaw Puzzle Player Puzzle Definition |
| JPR file extension | N/A | Oracle JDeveloper Model Project |
| JPS file extension | N/A | Stereospic JPEG Format |
| JPT file extension | Quest Software, Inc. | Jprobe Threadalyzer Memory Snapshot |
| JPW file extension | ESRI | ESRI JPEG World Format |
| JPX file extension | Joint Photographic Experts Group | JPEG 2000 Extended Image Format (ISO 15444-2) Format |
| JPZ file extension | N/A | Puzzle Solver Puzzle |
| JQ3SAVEGAME file extension | iWin, Inc. | Jewel Quest III Saved Game |
| JQX file extension | Microsoft Corporation | Microsoft Windows Help Related |
| JRC file extension | N/A | PCjr Cartridge ROM Format |
| JRF file extension | N/A | The Jumbot Bot Level Navigation |
| JRL file extension | BioWare | BioWare Aurora Game Engine Journal |
| JRPRINT file extension | Jaspersoft | JasperReports Print Format |
| JRS file extension | Microsoft | Extensible Storage Engine (ESE) Reserve Transaction Log Format |
| JRTF file extension | JAmes OS | JAmes OS Rich Text Format |
| JRXML file extension | Jaspersoft | JasperReports Layout Format |
| JRZ file extension | Sony | Sony Playstation Portable Game Data Format |
| JS file extension | N/A | JavaScript Format |
| JSA file extension | Adobe Systems Incorporated | JRun Server Application |
| JSB file extension | Freedom Scientific, Inc. | JAWS Script Binary |
| JSC file extension | N/A | JavaScript Config |
| JSD file extension | Jazer Solutions | Jazer Financial Format |
| JSDA file extension | Jazer Solutions | Jazer Data Format |
| JSE file extension | N/A | JScript Encoded Script Format |
| JSF file extension | Project64 | Project64 Joystick Settings Format |
| JSFL file extension | Adobe Systems | Flash JavaScript Format |
| JSH file extension | Freedom Scientific | JAWS Script Header Format |
| JSI file extension | Freedom Scientific, Inc. | JAWS Personalized Settings |
| JSK file extension | COWON America, Inc. | JetAudio |
| JSL file extension | Corel Corporation | Corel PaintShop Photo Pro Shapes |
| JSM file extension | Freedom Scientific, Inc. | JAWS Script Message |
| JSML file extension | The NSR Physiome Project | JSim Model |
| JSN file extension | JetSoft Co. | Shield Now Shield |
| JSO file extension | N/A | Compressed ISO Image |
| JSON file extension | N/A | JavaScript Object Notation Format |
| JSONP file extension | N/A | JSON-with-padding Source Code |
| JSP file extension | Oracle | JAVA Server Page Format |
| JSPA file extension | N/A | Java Servlet Alias Format |
| JSPF file extension | Oracle | Java JSP Fragment |
| JSPX file extension | N/A | XML Java Server Page |
| JSR file extension | N/A | Job Safety Report Definition |
| JSS file extension | JACOsub | JACOSub Subtitle Format |
| JST file extension | Oracle | Java Server Page |
| JSV file extension | Steffen Webe | Java Structure Viewer |
| JSX file extension | Adobe Systems | Adobe After Effects Script Format |
| JSXBIN file extension | Adobe Systems | Binary JavaScript Format |
| JSXINC file extension | Adobe Systems | ExtendScript Included Script Format |
| JT file extension | N/A | JT Open CAD Format |
| JTB file extension | Oracle Corporation | JTB JavaCC Grammar |
| JTBACKUP file extension | Shubham Kedia | Just Type Notes Backup Format |
| JTD file extension | Justsystems | Ichitaro Document |
| JTDC file extension | Justsystems | Ichitaro Compressed Document |
| JTG file extension | ARM Holdings plc | Joint Test Action Group Configuration |
| JTK file extension | Oracle Corporation | Sun Microsystems Java Toolkit |
| JTL file extension | Apache Software Foundation | JMeter Test Results |
| JTP file extension | Microsoft | Microsoft Windows Journal Template Format |
| JTPL file extension | IBM | Rational Application Developer WebContent Theme Template |
| JTS file extension | Cyberlink | JVC Cyberlink AVCHD Video Format |
| JTT file extension | Justsystems | Ichitaro Document Template |
| JTV file extension | J. River | JRiver Media Center Recorded TV Format |
| JTX file extension | Microsoft | ESE Transaction Log |
| JUDE file extension | N/A | JUDE Project Format |
| JVSG file extension | JVSG | Video Surveillance Project |
| JVT file extension | JRiver, Inc. | JRiver Recorded Video |
| JW file extension | N/A | Microsoft WordPad |
| JWC file extension | NTI Corporation | JewelCase Maker Saved |
| JWG file extension | Oracle Corporation | Java |
| JWL file extension | Roxio | Roxio Jewel Case Format |
| JWR file extension | Rocket Software, Inc. | LegaSuite GUI J Walk Runtime |
| JWS file extension | BEA Systems | Oracle WebLogic Server Java Web Services Format |
| JXR file extension | Microsoft | JPEG XR Image |
| JZ file extension | JamesZhu Inc. | JamesZhu Internet Browser Database |
Web Developer acting on his own, author of Internet solutions facilitating working with new technologies for less advanced users. Internet maniac.
