| kbwc | Knowledge Master KBWC Data |
| kbx | GnuPG Keybox File |
| kcc | KeywordConvert Combined List |
| kcd | Kayak Network Definitions Data |
| kces | eXtendable Wad Editor KCES Data |
| kcey | eXtendable Wad Editor KCEY Data |
| kcf | KMESS Cross-section Data |
| kcl | KeywordConvert List |
| kcm | KonyvCalc Data |
| kco | Kwalitan Codes Data |
| kcs | Keep and Share Offline Calendar Data |
| kct | Knit Visualizer 1.0 Chart |
| kct | Kwalitan Categories Data |
| kd | Agilent ChemStation Kinetic Disk Data |
| kd3 | Yayoi Kaikei Accounting Data |
| kdb | Doobs Database |
| kdb | KeePass v1 Password Database |
| kdb | Key Database File |
| kdb | kinodb Database |
| kdbp | KeePass Fast KDBP Data |
| kdbx | KeePass v2 Password Database |
| kdc | Kaspersky Anti-virus Database |
| kdd | Adobe Authorware Knowledge Display Data |
| kdevprj | KDevelop DevHelp Documentation |
| kdf | KARMA Triton Data |
| kdf | KMESS Detector Data |
| kdf | VisiQuest Standard Data Format File |
| kdi | KD Player Skin Image |
| kdl | Kill The Deadline Data File |
| kdo | Kudo Image Browser Data |
