| .C4D | MAXON Computer | 3D-billedfiler | Cinema 4D Model File | Adobe After Effects | Adobe Systems Incorporated |
| .CACHE | Various Developers | Ikke Almindelige Filer | Cache File | Adobe Photoshop | Adobe Systems Incorporated |
| .CAL | Newera Software Technology, Inc. | Rasterbilledfiler | CALS Raster File | Adobe Photoshop | Adobe Systems Incorporated |
| .CALS | Newera Software Technology, Inc. | Rasterbilledfiler | CALS Raster File | Adobe Photoshop | Adobe Systems Incorporated |
| .CATPRODUCT | Dassault Systèmes | CAD-filer | CATIA V5 Assembly File | Adobe Acrobat DC | Adobe Systems Incorporated |
| .CCT | Adobe Systems Incorporated | Datafiler | Director Protected Cast Resource | Adobe Director | Adobe Systems Incorporated |
| .CDR | Corel | Vektorbilledfiler | CorelDRAW Vector Image File | Adobe Illustrator CC | Adobe Systems Incorporated |
| .CEF | Richard Stott | Datafiler | Class Action Gradebook Elementary File | Adobe Illustrator CC | Adobe Systems Incorporated |
| .CEL | Affymetrix | Datafiler | Affymetrix Probe Results File | Adobe Audition | Adobe Systems Incorporated |
| .CER | Microsoft Corporation | Webfiler | Internet Security Certificate | Adobe Acrobat DC | Adobe Systems Incorporated |
| .CFA | Frontline | Datafiler | ComProbe Analyzer Capture File | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .CFC | Adobe Systems Incorporated | Udviklerfiler | ColdFusion Component File | Adobe Dreamweaver | Adobe Systems Incorporated |
| .CFG | Unknown Developer | Udviklerfiler | Configuration File | Brackets | Adobe Systems Incorporated |
| .CFM | Adobe Systems Incorporated | Webfiler | ColdFusion Markup File | Adobe Dreamweaver | Adobe Systems Incorporated |
| .CGM | Unknown Developer | Vektorbilledfiler | Computer Graphics Metafile | Adobe Illustrator CC | Adobe Systems Incorporated |
| .CGR | Dassault Systèmes | CAD-filer | CATIA Graphical Representation File | Adobe Acrobat DC | Adobe Systems Incorporated |
| .CHA | Snak Software | Webfiler | IRC Chat Configuration File | Adobe Photoshop CC | Adobe Systems Incorporated |
| .CIN | Kodak | Rasterbilledfiler | Kodak Cineon Bitmap File | Adobe SpeedGrade | Adobe Systems Incorporated |
| .CLR | Adobe Systems Incorporated | Ikke Almindelige Filer | Animate Color Set | Adobe Animate CC 2017 | Adobe Systems Incorporated |
| .CLX | IBM | Datafiler | Rational XDE | Adobe Illustrator CC | Adobe Systems Incorporated |
| .CMX | Corel | Vektorbilledfiler | Corel Metafile Exchange Image File | Adobe Illustrator CC | Adobe Systems Incorporated |
| .COLLECTION | Adobe Systems Incorporated | Datafiler | Adobe Bridge Collection File | Adobe Bridge CC | Adobe Systems Incorporated |
| .CONFIG | Unknown Developer | Udviklerfiler | Configuration File | Brackets | Adobe Systems Incorporated |
| .CP | Apple | Udviklerfiler | Xcode C++ Source File | Adobe Captivate | Adobe Systems Incorporated |
| .CPD | Adobe Systems Incorporated | Datafiler | RoboHelp Cache Project Database | Adobe RoboHelp | Adobe Systems Incorporated |
| .CPI | Sony | Videofiler | AVCHD Video Clip Information | Adobe Premiere Pro CC | Adobe Systems Incorporated |
| .CPR | Steinberg | Lydfiler | Cubase Project | Adobe Captivate | Adobe Systems Incorporated |
| .CPS | Interscape | Spilfiler | The Powder Toy Save File | Adobe Captivate | Adobe Systems Incorporated |
| .CR2 | Canon Inc. | Kamera Ubehandlede Filer | Canon Digital Camera Raw Image File | Adobe Photoshop Elements | Adobe Systems Incorporated |
| .CRW | Canon Inc. | Kamera Ubehandlede Filer | Canon Raw CIFF Image File | Adobe Photoshop Elements | Adobe Systems Incorporated |
| .CS | Microsoft Corporation | Udviklerfiler | C# Source Code File | Adobe Dreamweaver | Adobe Systems Incorporated |
| .CSF | Intergraph Corporation | GIS-filer | GeoMedia Coordinate System File | Adobe Illustrator CC | Adobe Systems Incorporated |
| .CSH | Adobe Systems Incorporated | Ikke Almindelige Filer | Photoshop Custom Shapes File | Adobe Photoshop Elements | Adobe Systems Incorporated |
| .CSN | Adobe Systems Incorporated | Udviklerfiler | Adobe Code Snippet Document | Adobe Dreamweaver | Adobe Systems Incorporated |
| .CST | Smith Micro Software | Sideopsætningsfiler | Manga Studio Story File | Adobe Director | Adobe Systems Incorporated |
| .CT | Unknown Developer | Spilfiler | Cheat Engine Cheat Table | Adobe Photoshop | Adobe Systems Incorporated |
| .CTP | Cake Software Foundation | Udviklerfiler | CakePHP Template | Adobe Dreamweaver | Adobe Systems Incorporated |
| .CXT | Omron Corporation | Udviklerfiler | CX-Programmer Project Text File | Adobe Director | Adobe Systems Incorporated |
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