| 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 |
| jscsrc | JSCS Configuration Data |
| jshintrc | JSHint Configuration |
| jte | Eclipse Jakarta EE TCK Configuration |
| jup | Code Crusader User Preferences |
| jvd | JavaView Camera and Display Settings |
| jvi | Java Versant Interface Configuration |
| jvr | JavaView Configuration |
| jvs | JavaScript Proxy Autoconfig |
| kax | Kieker Configuration File |
| kbd | Autodesk 3D Studio MAX Keyboard Shortcuts |
| kbn | TeamSpeak Keybinding |
| kcf | Sony Ericsson HID Keypad Configuration |
| kfe | Koffiee Login Data |
| kfg | Adobe Acrobat Preflight Profile |
| kfp | KaraFun Karaoke Presets |
| kgr | SmartConfig Configuration Data |
| kik | Kickabout Settings |
| klc | Windows MKLC Keyboard Layout |
| kp04 | KPT Presets Data |
| ksr | Kiwi Syslog Rule |
| ktc | Attachmate KEA! Configuration |
| ktw | KeyTweak Configuration |
| kuip | Kingsoft Office Personalization |