| isp | Internet Sign-up Settings |
| iuux | Powerflex IUUX Configuration Data |
| ivc | InteliSea Vessel Configuration |
| ixi | ixiQuarks Preferences Data |
| ixw | ERDAS Imagine Workspace Layout |
| jaas | JAAS Configuration File |
| jai | Jaikoz Audio Tag Editor Settings |
| jap | jAlbum Settings |
| jarx | Jarx Configuration |
| jcf | JAWS Settings Data |
| jcp | Jesusonic Preset File |
| jdw | BlackBerry JDE Workspace |
| jeq | JetAudio Equalizer Settings |
| jgcscs | EditPad Custom Syntax Coloring Scheme |
| jgf | JAWS Configuration |
| jkm | JAWS Key Map Data |
| jmd | Corel Paint Shop Pro Image Map Settings |
| joboptions | Adobe Acrobat Distiller Job Options |
| joe | JOE Configuration |
| jpif | Delft-FEWS Java Runtime Options Data |
| jscsrc | JSCS Configuration Data |
| jshintrc | JSHint Configuration |
| jte | Eclipse Jakarta EE TCK Configuration |
| jti | JavaTest Configuration Data |
| jtrrcfg | SUMO jtrrouter Configuration |
| jup | Code Crusader User Preferences |
| jvd | JavaView Camera and Display Settings |
| jvi | Java Versant Interface Configuration |
| jvr | JavaView Configuration |
| jvs | JavaScript Proxy Autoconfig |