| crash | Mac OS X Crash Log |
| crf | MASM Cross-Reference Data |
| crn | Crunch Compressed Texture |
| cs | Visual C# .NET Class |
| csc | Ovation Pro C Script |
| csdef | Microsoft Azure Service Definition Schema |
| cshtml | Razor C# Web Page |
| csi | CR10X EdLog Source Code |
| csi | ContentServ Include |
| csig | SCons Content Signature |
| csl | Citation Style Language Document |
| csm | C++ Builder Precompiled Header |
| csn | Dreamweaver Code Snippet File |
| csn | Adobe Code Snippet Document |
| csp | RadGs Concept Server Page |
| csp | InterSystems Cache Server Page |
| csq | Microsoft Visual FoxPro Client-Server Query File |
| csx | Visual C# Script |
| ctc | Visual Studio Command Table Configuration |
| ctf | MATLAB Component Technology File |
| ctl | Visual Basic User Control Text |
| cto | Visual Studio Binary Command Table Output |
| ctp | CakePHP Template |
| ctrl | Oracle WebLogic Workshop Controls |
| cts | ABC Permanent Locations Data |
| ctsym | Visual Studio Command Table Symbols File |
| ctx | Visual Basic User Control Binary File |
| ctxt | BlueJ Context File |
| cu | CUDA Source Code |
| cuf | Turbo C Utilities Form Definition |
