| File Extension | File Type |
| C | UNIX Compact File Achive |
| C | Origin C Program File (OriginLab Corporation) |
| C | ADS Source Code (Autodesk, Inc.) |
| C | C/C++ Program File |
| C | Check Point Site Configuration for Secure Remote (Check Point Software Technologies Ltd.) |
| C | Desktop Color Separation Specification Cyan Layer |
| C | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| C V | Cvip File |
| C!_ | Audio Utility Midimach Compressed File |
| C#= | C# (Microsoft Corporation) |
| C++ | C++ Source Code |
| C-- | Sphinx C-- Source |
| C0 | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| C00 | Ventura Print File |
| C00 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C01 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C01 | Genesis 2000 (Genesis 2000, Inc.) |
| C02 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C02 | (C02-C38) Driveimage Ace File |
| C03 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C04 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C05 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C06 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C07 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C08 | Lord Of Destruction Game File |
| C08 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C09 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C1 | Pov-ray for Windows v3.1 Scenes Advanced Newltpot File (Persistence of Vision Raytracer Pty Ltd.) |
| C10 | WinAce Compressed File Split Portion of Compressed File (e-merge GmbH) |
| C13 | Charlie Packer |
| C2 | Pov-ray for Windows v3.1 Scenes Advanced Newltpot File (Persistence of Vision Raytracer Pty Ltd.) |
| C2C | CopyToDVD Project File (VSO-Software) |
| C2D | WinOnCD CD Image (Sonic Solutions) |
| C2E | NJStar Chinese Word Processor Dictionary File Index (NJStar Software Corp.) |
| C2I | Driver File |
| C2I | Tt File |
| C2L | Cequadrat WinonCD File |
| C2X | WinonCD File |
| C3 | Pov-ray for Windows v3.1 Scenes Advanced Newltpot File (Persistence of Vision Raytracer Pty Ltd.) |
| C39 | (C39-C56) Quicken Ace File |
| C3D | Cult3D Designer Intermediate File |
| C3D | Chem3D Chemical File (CambridgeSoft Corporation) |
| C3D | Coordinate 3D |
| C3D | Micrografx |
| C3E | Cype |
| C3T | Chem3D Chemical Template File |
| C4 | Unknown Apple II File (found on Golden Orchard Apple II CD Rom) |
| C4 | Joint Engineering Data Management (JEDMICS) DoD Engineering Data Format |
| C4 | Edmics |
| C4D | Cinema 4D 3D Model (MAXON Computer GmbH) |
