| .C4 | Northrop Grumman Corporation | Raster Image Files | JEDMICS Image File | Trix DrawingCenter | Trix Systems |
| .CA1 | Piotr Fusik | Raster Image Files | CrackArt Picture Image | Recoil | Piotr Fusik |
| .CA3 | Casio Computer Co., Ltd. | Raster Image Files | Casio WK-1800 Save All Data | WK-1800 | Casio Computer Co., Ltd. |
| .CAL | Newera Software Technology, Inc. | Raster Image Files | CALS Raster File | Adobe Photoshop | Adobe Systems Incorporated |
| .CALS | Newera Software Technology, Inc. | Raster Image Files | CALS Raster File | Adobe Photoshop | Adobe Systems Incorporated |
| .CAM | Ucamco | Raster Image Files | Gerber CAM Job File | CadSoft EAGLE | Autodesk, Inc. |
| .CAN | Canon Inc. | Raster Image Files | Canon Navigator Fax File | Canon MP Navigator | Canon Inc. |
| .CARD | GameHouse | Raster Image Files | Funkiball Adventure Game File | Funkiball Adventure | GameHouse |
| .CCH | Microsoft Corporation | Raster Image Files | .NET Security Resolution Cache File | Microsoft .NET Framework | Microsoft Corporation |
| .CCI | Piotr Fusik | Raster Image Files | Champions' Interlace Compressed Picture Image | Recoil | Piotr Fusik |
| .CCRF | Calcomp | Raster Image Files | Calcomp Raster Bitmap Image File | ArcView | ESRI |
| .CDC | Autodesk, Inc. | Raster Image Files | AutoCAD DesignCenter Preview Cache File | Autodesk AutoCAD | Autodesk, Inc. |
| .CDG | Open Source | Raster Image Files | Compact Disc Plus Graphics Image | Nullsoft Winamp | Nullsoft |
| .CE | Digital Vision | Raster Image Files | ComputerEyes Image | XnView MP | XnSoft |
| .CHART | Interscape | Raster Image Files | Feedback Chart File | Microsoft Notepad | Microsoft Corporation |
| .CHE | Procedimientos-Uno, S.L. | Raster Image Files | CHwinEHE Project Files | CHwinEHE | Procedimientos-Uno, S.L. |
| .CID | Omar F. Reis | Raster Image Files | Navigator Software Chart Image Description File | Navigator | Omar F. Reis |
| .CIN | Kodak | Raster Image Files | Kodak Cineon Bitmap File | Adobe SpeedGrade | Adobe Systems Incorporated |
| .CIT | Intergraph Corporation | Raster Image Files | Intergraph Bitmap Image File | Intergraph SG&I software | Intergraph Corporation |
| .CLIP | CELSYS | Raster Image Files | Clip Studio Format File | CELSYS Clip Studio Paint Pro | CELSYS |
| .CMP | Microsoft Corporation | Raster Image Files | Windows Connection Manager Profile | Microsoft Windows Server 2016 | Microsoft Corporation |
| .CMR | CMA Coach | Raster Image Files | Coach Results File | CMA Coach | CMA Coach |
| .CPC | Cartesian Products, Inc. | Raster Image Files | CPC Compressed Image File | Internet Explorer | Microsoft Corporation |
| .CPD | Adobe Systems Incorporated | Raster Image Files | RoboHelp Cache Project Database | Adobe RoboHelp | Adobe Systems Incorporated |
| .CPS | Interscape | Raster Image Files | The Powder Toy Save File | The Powder Toy | Interscape |
| .CPT | Corel | Raster Image Files | Corel Photo-Paint Image | Corel Presentations X8 | Corel |
| .CPX | Oracle Corporation | Raster Image Files | Oracle ADF Binding Context File | Oracle JDeveloper | Oracle Corporation |
| .CSF | Intergraph Corporation | Raster Image Files | GeoMedia Coordinate System File | Intergraph GeoMedia | Hexagon Geospatial |
| .CT | Unknown Developer | Raster Image Files | Cheat Engine Cheat Table | Cheat Engine | Open Source |
| .CUT | Various Developers | Raster Image Files | Dr. Halo Bitmap Image File | Lemkesoft GraphicConverter | Lemkesoft |
| .CVP | Symantec Corporation | Raster Image Files | WinFax Cover Page | WinFax | Delrina |
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