| kdl | Kill The Deadline Data File |
| kdo | Kudo Image Browser Data |
| kdr | Kinetica Data File |
| kds | KD Player Skin |
| kdt | Medbasin Evaporation Data |
| kdx | Google Earth Import Definition |
| kdz | Kaspersky Anti-virus Database |
| ked | KEDIT Macro File |
| ked | KEDIT Macro Library |
| keepsafe | KeepSafe Folder |
| kef | KAPA mpi Exported Data |
| keg | Kieler Editor for Graphs Model |
| kegdi | Kieler Editor for Graphs GMF Notation Model |
| kek | IBM Personal Communications KEK Storage |
| ken | Player Cdcheck Compressed Data |
| kex | KEDIT Macro File |
| kexi | Kexi Database |
| kexic | Kexi Database Connection Data |
| kexis | Kexi Database Shortcut |
| key | Tinker Keyword Parameters |
| key | SmartWare Database Key File |
| keychain | Mac OS X Keychain |
| keyring | Java Key Store |
| keystore | Java Key Store |
| kez | CA 01 Customer Product Numbers Data |
| kfl | Kwalitan Filter Data |
| kfo | Konica Minolta Bizhub Copier Overlay Data |
| kfr | Kalles Fraktaler 2 Data |
| kfx | Kofax Capabilities File |
| kgm | KeyTERRA-FIRMA Ground Model Data |
| kh | Khmer-Protocols Hash Table |
| khd | Microsoft Dynamics AX Kernel Help Documentation |
| khf | Kwalitan Tree Structure |
| khs | Kwalitan History Data |
| kids | SAM Kestrel Sequence Id Data |