| .job |
MetaCAM Nest Job File |
| .jvsg |
Video Surveillance Project |
| .jas |
Cheetah3D Model File |
| .jtv |
JRiver TV File |
| .jam |
Line 6 Device Recording |
| .jbig2 |
JBIG2 |
| .j3o |
jMonkeyEngine 3D Scene |
| .jap |
Nonogram Puzzle File |
| .jks |
Java Keystore File |
| .jceks |
JCEKS Keystore File |
| .j |
Java Source File |
| .jpe |
JPEG Image |
| .jbig |
Joint Bi-level Image Group File |
| .jfi |
JPEG File Interchange Image |
| .j2k |
JPEG 2000 Image |
| .jbk |
Juno Backup File |
| .jbf |
Paint Shop Pro Browser Cache File |
| .jpf |
JPEG 2000 Image File |
| .jwl |
Roxio Jewel Case File |
| .jsxbin |
Binary ExtendScript Script File |
| .jdc |
JDownloader Links File |
| .jtx |
ESE Transaction Log |
| .ja |
Jet Archive |
| .jag |
Jagex Data File |