| ksd | KeepSafe Data |
| kse | Keepsake Studio Export File |
| kseqs | SAM Kestrel Sequence Database |
| ksg | Kwalitan Segment File |
| ksi | Alloy Blending System KSI Data |
| ksk | Adobe Illustrator Kinsoku Set |
| ksl | Karaoke Song List Creator Data |
| kss | FabTrol MRP KISS File |
| kt3 | KeyText v3 Data |
| ktb | BRLTTY Key Tables Data |
| ktd | Microsoft Dynamics AX Kernel Text Data |
| ktf | KeyTruss Truss Data |
| kti | Kelvin TOP-SET Investigator Data |
| kti | BRLTTY Subtables Data |
| ktl | Knowmia Teach Lesson File |
| ktr | KeyTruss Truss Data |
| ktr | Kettle Transformation File |
| ktt | KeyText Data |
| ktx | Kwalitan Text |
| ku | my Knowledge Explorer Knowledge Unit |
| kud | Kaspersky Lab Unicode Application Description |
| kup | Karaoke Song List Creator Database |
| kv3 | KM-NET Viewer v4 Workspace |
| kvc | Knit Visualizer 2.0 Chart |
| kvk | Keyman Desktop Virtual Keyboard File |
| kvl | Knit Visualizer Library |
| kvml | KWordQuiz Data |
| kvp | Key-Value Pair Data |
| kvt | KVIrc Theme Data |
| kvx | Voxel Data |
| kvx | KM-NET Viewer v5 Workspace |
| kwa | KWIVER Video Data |
| kwb | Kwalitan Work File |
| kwb | BrailleNote KeyWord Braille |
| kwc | Flipnote Studio 3D Comments Data |