List of Data File Formats Starting with the Letter "J"
| .j01 | File Extension from ADP Payroll Company |
| .jad | Java Application Descriptor extension (for installing MIDlets) |
| .jar | Java archive file |
| .jas | Graphics |
| .jav | Java source code file |
| .java | Java source code file |
| .jbc | Jam Byte-Code Hex file |
| BestCrypt File | |
| .jbd | Datafile (SigmaScan) |
| .jbf | Paint Shop Pro browser file |
| .jbk | Juno Backup file |
| .jbr | Jasc Paint Shop Pro Brush |
| .jbx | Project file (Project Scheduler 4) |
| .jdt | Accelio Capture Classic Filler |
| .jef | Janome NH10000 Sewing Machine file |
| .jet | Fax (Hybrid JetFax) |
| .jff | Bitmap graphics (JPEG File Interchange Format) |
| .jfif | JPEG image |
| .jfx | J2 Fax File |
| .jhtml | Dynamo Server Page |
| .jif | JPEG/JIFF Image |
| Jeff's Image Format | |
| .jmx | JMeter file |
| .jnb | Sigma Plot Workbook file |
| .jnl | Ingres Journal file |
| .jnlp | Java Web Start file |
| .jnt | Windows Journal Note file |
| .job | Job file |
| Task Scheduler Task Object | |
| AI Research file | |
| QuestVision Vector Graphics file | |
| .jor | Journal file SQL |
| .jou | Journal backup (VAX Edt editor) |
| .jp2 | JPEG 2000 file |
| .jpc | Graphics (Japan PIC) |
| .jpeg | JPEG image |
| .jpf | JPEG 2000 file |
| .jpg | Bitmap graphics (Joint Photography Experts Group) |
| .jps | Stereo Image |
| .jpx | JBuilder Project file |
| .js | Microsoft Scripting Language "JScript" file extension |
| .jsd | eFAX Jet Suite Document |
| .jse | JScript Encoded Script file |
| .jsf | Fireworks Batch Script file |
| .jsh | Henter-Joyce, Inc. Jaws Script Header file |
| .json | JavaScript Object Notation file |
| .jsp | Java Server page |
| .jtf | Fax (Hayes JT Fax) |
| Bitmap graphics (JPEG Tagged Interchange Format) | |
| .jtp | Jetform file |
| .jup | (New Planet Software) Code Crusader user's project preferences file |
| .jw | Text document (JustWrite) |
| .jwl | Library (JustWrite) |
| .jwp | Easy CD Creator Label file |
| JWP Document | |
| .jxr | JPEG XR file |
| .jzz | Spreadsheet (Jazz) |
