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