| .J1 | Unknown Developer | Arquivos de dados | EDIT Compiler JEDEC Boundary File | Unknown Software | Unknown Developer |
| .JASPER | Jaspersoft | Arquivos de dados | JasperReports Data File | JasperReports | Jaspersoft |
| .JAW | JustSystems | Arquivos de dados | Ichitaro File | Ichitaro | JustSystems |
| .JBB | Damian Brunold | Arquivos de dados | Jbead Data | Jbead | Damian Brunold |
| .JBD | Symantec Corporation | Arquivos de dados | Norton Antivirus Definiton Update File Format | Norton Security | Symantec Corporation |
| .JBI | Yaskawa Motoman | Arquivos de dados | Motoman Robot Job File | MotoPallet EG | Yaskawa Motoman |
| .JBW | Scitor | Arquivos de dados | Scitor Project Scheduler Schedule Data | Project Scheduler | Scitor |
| .JBX | Unknown Developer | Arquivos de dados | Project Scheduler Data | Unknown Software | Unknown Developer |
| .JCAMP | Joint Committee on Atomic and Molecular Physical Data (JCAMP-DX ) | Arquivos de dados | JCAMP Standard NMR Data Format | Unknown Software | Unknown Developer |
| .JCC | Open Source | Arquivos de dados | Code Crusader Project Data | Code Crusader | Open Source |
| .JCD | Hou Yantang | Arquivos de dados | FlashGet Saved Data | FlashGet | Hou Yantang |
| .JCE | Glenn Rosenthal | Arquivos de dados | JWPce File | JWPce | Glenn Rosenthal |
| .JCK | Microsoft Corporation | Arquivos de dados | Microsoft Liquid Motion JACK Scene Escription | Liquid Motion | Microsoft Corporation |
| .JCV | JC Video | Arquivos de dados | JC Video Systems Data | Unknown Software | Unknown Developer |
| .JD | Orchid Technology KK | Arquivos de dados | Jigsaw Terminal File | Jigsaw Platform | Orchid Technology KK |
| .JDB | Symantec Corporation | Arquivos de dados | Symantec Endpoint Protection Update File | Symantec EndPoint Protection 12 | Symantec Corporation |
| .JDBG | Open Source | Arquivos de dados | Embedded JCL Debug Information | Project JEDI | Open Source |
| .JDL | European Grid Infrastructure | Arquivos de dados | gLite Job Description Language File | gLite | European Grid Infrastructure |
| .JDT | Adobe Systems Incorporated | Arquivos de dados | Accelio Capture Classic Filler Data | Accelio Capture Classic Filler | Adobe Systems Incorporated |
| .JDX | Page Scholar Inc | Arquivos de dados | JSpell Dictionary File | JSpell | Page Scholar Inc |
| .JEF | Janome Sewing Machine Co., Ltd. | Arquivos de dados | Janome Embroidery Format | Janome Customizer 11000 | Janome Sewing Machine Co., Ltd. |
| .JFD | Freedom Scientific | Arquivos de dados | JAWS Synopsis Data | JAWS | Freedom Scientific |
| .JGD | Corel | Arquivos de dados | Corel PaintShop Photo Pro Gradients File | PaintShop Pro | Corel |
| .JGF | Freedom Scientific | Arquivos de dados | JAWS Ini File | JAWS | Freedom Scientific |
| .JIO | INRIA | Arquivos de dados | Join-Calculus JCC Compiled Interface | Join-Calculus | INRIA |
| .JLP | Neowin | Arquivos de dados | Jumplist Extender File | Jumplist Extender | Neowin |
| .JMP | SAS Institute Inc. | Arquivos de dados | JMP Data File | SAS | SAS Institute Inc. |
| .JMS | Half-Baked Software | Arquivos de dados | Masher Project | Hot Potatoes | Half-Baked Software |
| .JNL | Actian Corporation | Arquivos de dados | Ingres Journal File | Ingres Database | Actian Corporation |
| .JNT | Microsoft Corporation | Arquivos de dados | Windows Journal File | Microsoft Windows Journal | Microsoft Corporation |
| .JOB | Metamation | Arquivos de dados | MetaCAM Nest Job File | MetaCAM Nesting | Metamation |
| .JOBOPTIONS | Adobe Systems Incorporated | Arquivos de dados | Adobe Joboptions File | Adobe Illustrator CC | Adobe Systems Incorporated |
| .JOC | ConTEXT Project | Arquivos de dados | Context4 DOS Word Processor File | ConTEXT | ConTEXT Project |
| .JOINED | Freebyte | Arquivos de dados | HJ-Split Data File | Freebyte HJSplit for Java | Håkan Gustavsson |
| .JOT | King Stairs | Arquivos de dados | Jot+ Notes Note Data | Jot+ Notes | King Stairs |
| .JP4 | Open Source | Arquivos de dados | Elphel Project Data | Elphel Project | Open Source |
| .JP5 | Electric Quilt | Arquivos de dados | Electric Quilt Data | Electric Quilt | Electric Quilt |
| .JPC | Joint Photographic Experts Group | Arquivos de dados | JPEG 2000 Code Stream File | Adobe Illustrator CC | Adobe Systems Incorporated |
| .JPF | Joint Photographic Experts Group | Arquivos de dados | JPEG 2000 Image | Adobe Illustrator CC | Adobe Systems Incorporated |
| .JPH | Quest Software | Arquivos de dados | JProbe Memory Snapshot File | JProbe | Quest Software |
| .JPL | Sonic Foundry | Arquivos de dados | Siren Jukebox File | Siren Jukebox | Sonic Foundry |
| .JPN | Microsoft Corporation | Arquivos de dados | Windows Japanese Noise-Word List File | Microsoft Notepad | Microsoft Corporation |
| .JPT | Quest Software | Arquivos de dados | Jprobe Threadalyzer Memory Snapshot | JProbe | Quest Software |
| .JPX | Embarcadero Technologies | Arquivos de dados | JBuilder Project | JBuilder | Embarcadero Technologies |
| .JQX | Microsoft Corporation | Arquivos de dados | Microsoft Windows Help-Related File | Microsoft Windows | Microsoft Corporation |
| .JRXML | Jaspersoft | Arquivos de dados | JasperReports Layout File | iReport Designer | Jaspersoft |
| .JSD | Jazer Solutions | Arquivos de dados | Jazer Data File | Jazer | Jazer Solutions |
| .JSF | Adobe Systems Incorporated | Arquivos de dados | Java Script Command File | Adobe Fireworks | Adobe Systems Incorporated |
| .JSK | Cowon Systems | Arquivos de dados | JetAudio File | jetAudio | Cowon Systems |
| .JSM | Mozilla | Arquivos de dados | Firefox JavaScript Module | Mozilla Firefox | Mozilla |
| .JSML | Physiome Project | Arquivos de dados | JSim Model File | JSim | Physiome Project |
| .JSONLD | Microsoft Corporation | Arquivos de dados | Microsoft Visual Studio Data File | Microsoft Visual Studio | Microsoft Corporation |
| .JSPROJ | Microsoft Corporation | Arquivos de dados | Microsoft Visual Studio Data File | Microsoft Visual Studio | Microsoft Corporation |
| .JTB | Wanjun Wang | Arquivos de dados | JTB JavaCC Grammar Data | JTB | Wanjun Wang |
| .JTL | Apache Software Foundation | Arquivos de dados | JMeter Test Results Data File | Apache JMeter | Apache Software Foundation |
| .JW | Microsoft Corporation | Arquivos de dados | Microsoft WordPad Document | Microsoft WordPad | Microsoft Corporation |
| .JWG | Oracle Corporation | Arquivos de dados | Java Data | Java | Oracle Corporation |
| .JWL | Roxio | Arquivos de dados | Roxio Jewel Case File | Roxio Creator NXT Pro 5 | Roxio |
| .JWP | Sonic Solutions | Arquivos de dados | Easy CD Creator Label File | Roxio Easy CD Creator | Roxio |
| .JWR | Rocket Software | Arquivos de dados | LegaSuite GUI J Walk Runtime Data | LegaSuite | Rocket Software |
| .JWRP | Benoit Widemann | Arquivos de dados | JoliWrite File | JoliWrite | Benoit Widemann |
| .JWW | Open Source | Arquivos de dados | Java Web-Workflows Data | Java Web-Workflows | Open Source |
| .JXX | Yamaha Corporation | Arquivos de dados | Yamaha SY77 Audio Data File | Yamaha SY77 | Yamaha Corporation |
de 1 
