| cetool | Windows CE Plugin |
| cfb | Microsoft Compound File Binary |
| cfc | ColdFusion Component File |
| cfm | ColdFusion Markup Language |
| cfml | ColdFusion Markup Language |
| cfo | Borland Turbo C Form Object |
| cga | CryENGINE Geometry Animation |
| cgf | Amazon Lumberyard Static Geometry Data |
| cgf | ProWorx NXT Codegen Batch |
| cgf | CryENGINE Geometry Format Data |
| cgfx | Nvidia CgFX Shader |
| cgi | RAD Studio CodeGuard Configuration |
| cginc | Unity Custom Shader Include |
| cgl | RAD Studio CodeGuard Log |
| cgr | Quest3D Channel Group File |
| cgt | GOLD Parser Compiled Grammar Table |
| cgvp | Nvidia Cg Toolkit XML Data |
| cham | Compiled HAM |
| changes | Squeak Changes Data |
| chef | Chef Source Code |
| chh | Borland C++ Header |
| chi | C To Haskell Interface File |
| chr | Amazon Lumberyard Character Asset Data |
| chs | Haskell Source With C Hooks |
| cic | Hitachi Ladder Editor Circuit Comment |
| ciq | CONNX InfoNaut Query |
| cjs | CommonJS Script |
| ck | ChucK Source Code |
| ckbx | Cricket Audio XML Bank Description |
| ckg | Kokogut C Output File |