| .CAJ | National Project Research Center of CD | File con layout di pagina | Chinese Academic Journal File | CNKI CAJViewer | National Project Research Center of CD |
| .CAL | Newera Software Technology, Inc. | File con layout di pagina | CALS Raster File | Adobe Photoshop | Adobe Systems Incorporated |
| .CBF | Tailwag Software | File con layout di pagina | Calendar Builder File | Calendar Builder | Tailwag Software |
| .CBW | Open Source | File con layout di pagina | ComicRack Webcomics Data | ComicRack | Open Source |
| .CC5 | Broderbund | File con layout di pagina | Calendar Creator Document | Calendar Creator | Broderbund |
| .CD2 | Avery Dennison | File con layout di pagina | Click'N Design 3D File | Click'N Design 3D | Avery Dennison |
| .CDF | Wolfram Research | File con layout di pagina | Computable Document Format File | Wolfram Research CDF Player | Wolfram Research |
| .CH3 | Harvard Graphics | File con layout di pagina | Harvard Graphics DOS Chart File | ACD Systems Canvas | Microsoft Corporation |
| .CLT | Clarity Legal | File con layout di pagina | Clarity Legal Transcript File | Clarity Legal Viewer | Clarity Legal |
| .COV | Microsoft Corporation | File con layout di pagina | Fax Cover Page File | Microsoft Fax Cover Page Editor | Microsoft Corporation |
| .CP2 | Unknown Developer | File con layout di pagina | Compel V2 Presentation | Unknown Software | Unknown Developer |
| .CPE | Microsoft Corporation | File con layout di pagina | Fax Cover Page File | Microsoft Fax Cover Page Editor | Microsoft Corporation |
| .CPH | Corel | File con layout di pagina | Corel Print House File | Corel Print House | Corel |
| .CPY | Autodesk, Inc. | File con layout di pagina | 3ds Max Copy Track File | Autodesk 3ds Max | Autodesk, Inc. |
| .CSD | Valve | File con layout di pagina | Steam Game Data Backup File | Steam | Valve |
| .CST | Smith Micro Software | File con layout di pagina | Manga Studio Story File | Manga Studio | Smith Micro Software |
| .CW | NCH Software | File con layout di pagina | CardWorks Template | CardWorks | NCH Software |
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