| j2b | Jazz Jackrabbit 2 Music |
| j2d | Jazz Jackrabbit Game Data |
| j2e | Jazz Jackrabbit 2 Episode Data |
| j2h | Jazz Jackrabbit 2 Highscores Data |
| j2i | Jazz Jackrabbit 2 Internet Link Data |
| j2l | Jazz Jackrabbit 2 Level Data |
| j2m | Jazz Jackrabbit 2 Macro |
| j2s | Jazz Jackrabbit 2 Language Data |
| j2si | Jazz Jackrabbit 2 Internet Server Link Data |
| j2t | Jazz Jackrabbit 2 Tile Set |
| j2v | Jazz Jackrabbit 2 Video |
| ja | Trainz Jet Archive |
| jag | RuneScape Data |
| jap | QNonogram Puzzle Data |
| jbl | Doom Scene Add-on Data |
| jcr | QNonogram Puzzle Data |
| jfl | Traffic Giant Data |
| jg4 | BigJig Jigsaw Data |
| jg6 | BigJig Jigsaw Data |
| jhh | Tetris Online Poland Game Data |
| jigsaw | Jigsaw Explorer Saved Game |
| jit | AIKA Online Texture Data |
| jkb | Jedi Knight Bot File |
| jkl | Star Wars: Jedi Knight Game Data |
| jn1 | Jill of the Jungle Game Data |
| jnc | Jack Nicklaus 6 Course Data |
| jnk | Starpoint Gemini 2 Junkyard Data |
| joi | XBoard Join Conferences Data |
| jp6 | Atlantis Evolution Game Data |
| jp6 | Return to Mystery Island Data |
| jp6 | The Egyptian Prophecy Game Data |
| jpk | Dark Blood Online Game Data |
| jpp | Jigsaw Puzzle Player Data |
| jr2 | Fishing Simulator 2 Addon |
| jrf | Panzer Commander Game Data |
