| iwxdata | iWorx LabScribe Data |
| ix | dtSearch Desktop Index |
| ix1 | Rebel Chess Data |
| ix2 | Corel WordPerfect Address Book |
| ixb | Ulead Disc Image |
| ixc | ArcVIEW Geocode Coverage Index |
| ixf | Integration Exchange Format File |
| ixl | DB/TextWorks Database Indexed List |
| ixo | LightCycler v4 Experiment Data |
| ixr | XL Reporter Template |
| ixs | ArcVIEW Geocode Index |
| ixw | Pedigree Central Database Index |
| ixy | ISIS v2 Schematic Data |
| j3d | Atari Jaguar 3D Object |
| j3md | JMonkey Engine Material data |
| j64 | Virtual Jaguar ROM Image |
| jacksum | Jacksum Checksum Data |
| jaf | Just A Frequency Logger Backup Data |
| jan | Janome Embroidery Design |
| jap | Nintendo 64 Japanese ROM Image |
| jaskin | jAlbum Skin |
| jbc | Jetico BestCrypt Container |
| jbd | SigmaScan Data |
| jbeam | BeamNG.drive Vehicle Definition Format Data |
| jbf | Paint Shop Pro Browser Cache |
| jbi | Motoman Robot Job |
| jbk | Juno Client Software Backup |
| jbm | Jbmgen Data |
| jc | FlashGet Partial Download |
| jc1 | FlashGet Partial Download |
