| .jl |
Julia Source Code File |
| .jclic |
JClic Project File |
| .jsh |
JAWS Script Header File |
| .jkm |
JAWS Key Map File |
| .jgcscs |
EditPad Custom Syntax Coloring Scheme File |
| .jkb |
Jedi Knight Bot File |
| .jdat |
J&ASoft Data File |
| .jbeam |
BeamNG Vehicle Definition Format |
| .jdp |
BlackBerry JDE Application Project |
| .jlr |
Juliar Source Code File |
| .jvs |
JavaScript Proxy Autoconfig File |
| .jrtf |
JAmes OS Rich Text File |
| .jpn |
Windows Japanese Noise-Word List File |
| .jarvis |
Jarvis Subscriber File |
| .joe |
JOE Document |
| .kit |
CodeKit File |
| .kpl |
Kids Programming Language File |
| .ks |
Kickstart File |
| .kv |
Kivy Language File |
| .kt |
Kotlin Source Code File |
| .kbs |
Keyboard Script File |
| .kor |
Windows Korean Noise-Words List File |
| .msg |
Outlook Mail Message |
| .m3u |
Media Playlist File |