| kev | QNX System Profiler Event Log |
| kfb | Pyke Knowledge Fact Base |
| kgi | Kokogut Module Interface File |
| kjp | KJP Source Code |
| kkm | Kkrunchy Map Data |
| kl | Haxial Compiler KL Source |
| kl3 | KL3 Source Code |
| km3 | Kernel MetaMetaModel File |
| kmk | VirtualBox kBuild Makefile |
| kmn | Keyman Developer Keyboard Source File |
| ko | Linux 2.6 Kernel Object |
| kodu | Kodu Game |
| kof | Kylix Options File |
| koi | Kokogut Module Interface File |
| kop | Kokogut Compiler Options File |
| kpp | Keyman Developer Product Installer Source File |
| kps | Keyman Developer Package Source File |
| kpz | Komodo IDE Compressed Package |
| kqb | Pyke Knowledge Question Base |
| krb | Pyke Knowledge Rule Base |
| krt | Visual FoxPro KRT File |
| ks | Mer Kickstart File |
| ksh | KSH Shell Script |
| ksql | KSQL Script |
| kss | Kinetic Style Sheet |
| ktx | OpenGL Texture Data |
| kv | Kivy Source Code |
| kvh | Key-Value-Hierarchy Format Data |
| kx | KiXtart Tokenized Script |
| kxf | Koda FormDesigner Data |
| kxx | Keyman Developer Encrypted Keyboard File |
| kzb | Kanzi Binary |
| lai | GNU Libtool Temporary Data |
| lap | Scheme Source Code |
| layout | Code::Blocks Layout File |