| ktr | Kettle Transformation File |
| ktr | KeyTruss Truss Data |
| ktspack | KeyTruss Truss Archive Data |
| 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 | KM-NET Viewer v5 Workspace |
| kvx | Voxel Data |
| kwa | KWIVER Video Data |
| kwb | BrailleNote KeyWord Braille |
| kwb | Kwalitan Work File |
| kwc | Flipnote Studio 3D Comments Data |
| kwe | kCura Win Edds Data |
| kwf | Kwalitan Word List |
| kwi | KIWI Navigation Data |
| kwm | WebMoney Key |
| kwo | KeyWallet Encrypted Password Storage |
| kws | KeyWallet Skin |
| kwt | BrailleNote KeyWord Text |
| kwu | KWUROHR Data |
| kwx | kCura Win Edds Export Data |
| kwy | Keepaway Framework Learning Curve Data |
| kwz | Flipnote Studio 3D Flipnote Data |
| kxp | Key Home Gourmet Data File |
| kxw | Pedigree Central Database Index |
| kxy | SUPCRT92 K Values File |