| .C0 | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .C0R | Odeon / Odeon Worldwide | Arquivos de dados | JAF Nokia BB5 Firmware Flash | JAF | Odeon / Odeon Worldwide |
| .C10 | e-merge GmbH | Arquivos de dados | WinAce Split Archive File | WinAce | e-merge GmbH |
| .C11 | SINTEF | Arquivos de dados | CARE-S InfoWorks User-Defined Pollutant Detail Data | CARE-S | SINTEF |
| .C11AMC | ClueTrust | Arquivos de dados | Cartographica/CartoMobile File | Cartographica | ClueTrust |
| .C11AMZ | ClueTrust | Arquivos de dados | Cartographica/CartoMobile File | Cartographica | ClueTrust |
| .C1DX | GrapeCity | Arquivos de dados | C1Report C1D Open XML Document | C1Report | GrapeCity |
| .C1P | Phase One | Arquivos de dados | Capture One Preview Data | Capture One | Phase One |
| .C1W | Phase One | Arquivos de dados | Capture One Work Data | Capture One | Phase One |
| .C3 | The POV-Team | Arquivos de dados | Pov-Ray For Windows 3.1 Scenes Advanced Newltpot | Pov-Ray | The POV-Team |
| .C3D | Motion Lab Systems | Arquivos de dados | Coordinate 3D File | C3Deditor | Motion Lab Systems |
| .C9 | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .CA | AT&T Labs | Arquivos de dados | Initial Telnet Cache | Unix | AT&T Labs |
| .CA1 | Piotr Fusik | Arquivos de dados | CrackArt Picture Image | Recoil | Piotr Fusik |
| .CAC | dBase, LLC | Arquivos de dados | dBASE IV Executable Data | dBase | dBase, LLC |
| .CAF | Apple | Arquivos de dados | Apple Core Audio File | Apple QuickTime Player | Apple |
| .CAH | Ulead Systems | Arquivos de dados | Ulead Photo Explorer Thumbnail Cache | Ulead Photo Express | Ulead Systems |
| .CALC | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .CALCULATOR | Unknown Developer | Arquivos de dados | Unknown Apple II File. (found On Golden Orchard Apple II CD Rom) | Atom | GitHub, Inc. |
| .CAP | Microsoft Corporation | Arquivos de dados | Network Monitor Packet Capture Data File | Microsoft Network Monitor | Microsoft Corporation |
| .CAR | Unknown Developer | Arquivos de dados | Car Explorer Data File | Car Explorer | Unknown Developer |
| .CAS | Autodesk, Inc. | Arquivos de dados | Autodesk Cascade License File | AutoCAD Architecture | Autodesk, Inc. |
| .CASTLE | Unknown Developer | Arquivos de dados | Unknown Apple II File. (found On Golden Orchard Apple II CD Rom) | Atom | GitHub, Inc. |
| .CAT | Microsoft Corporation | Arquivos de dados | Windows Catalog File | Microsoft Windows | Microsoft Corporation |
| .CAV | Comodo Group | Arquivos de dados | Comodo Virus Definitions File | Comodo Group Internet Security | Comodo Group |
| .CB4 | Actuate Corporation | Arquivos de dados | Actuate Analytics File | Actuate Analytics | Actuate Corporation |
| .CBC | Open Source | Arquivos de dados | Sony Portable Reader Comic E-book File | Calibre | Open Source |
| .CBI | IBM | Arquivos de dados | IBM System/360 Column Binary Formatted File | Unknown Software | Unknown Developer |
| .CBM | EaseUS | Arquivos de dados | EaseUS Todo Backup File | EaseUS Todo Backup | EaseUS |
| .CBO | Microsoft Corporation | Arquivos de dados | Microsoft Interactive Training File | Microsoft Windows | Microsoft Corporation |
| .CBZ | Open Source | Arquivos de dados | Comic Book Zip Archive File | Smith Micro StuffIt Deluxe | Smith Micro Software |
| .CC1 | Briggs Softworks | Arquivos de dados | Briggs Softworks Calendar Commander Data File | Calendar Commander | Briggs Softworks |
| .CC2 | Briggs Softworks | Arquivos de dados | Calendar Commander Calendar Data | Calendar Commander | Briggs Softworks |
| .CC3 | Marcus Humann | Arquivos de dados | CUEcards Data File | CUEcards 2000 | Marcus Humann |
| .CCA | IBM | Arquivos de dados | Cc:Mail Archive File | Microsoft Importer for Lotus ccMail Archives | Microsoft Corporation |
| .CCF | Interscape | Arquivos de dados | CryptLoad Container File | CryptLoad | CryptLoad |
| .CCH | Microsoft Corporation | Arquivos de dados | .NET Security Resolution Cache File | Microsoft .NET Framework | Microsoft Corporation |
| .CCJ | WordWeb Software | Arquivos de dados | Crossword Compiler Compiled Crossword Applet File | Crossword Compiler | WordWeb Software |
| .CCK | U.S. Department of Energy | Arquivos de dados | COMcheck Data File | COMcheck | U.S. Department of Energy |
| .CCP | Ambiera | Arquivos de dados | CopperCube JavaScript File | CopperCube | Ambiera |
| .CCR | Records For Living | Arquivos de dados | ASTM Continuity Of Care Record | Records For Living HealthFrame Viewer | Records For Living |
| .CCT | Adobe Systems Incorporated | Arquivos de dados | Director Protected Cast Resource | Adobe Director | Adobe Systems Incorporated |
| .CCV | Master Control Inc. | Arquivos de dados | Crytal Vision Report | CTMS | Master Control Inc. |
| .CD | Microsoft Corporation | Arquivos de dados | Visual Studio Class Diagram | Microsoft Visual Studio | Microsoft Corporation |
| .CD1 | DATAIR | Arquivos de dados | DATAIR Cafeteria Document System Data | DATAIR Cafeteria Plan Document System | DATAIR |
| .CDB | Nokia | Arquivos de dados | Symbian Phonebook Database | Nokia PC Suite | Nokia |
| .CDBCMSG | CONTACT Software | Arquivos de dados | CIM Database CMSG Data File | CIM Database | CONTACT Software |
| .CDE | Kubotek Corporation | Arquivos de dados | CADKEY Dynamic Extension | CADKEY | Kubotek Corporation |
| .CDF | Wolfram Research | Arquivos de dados | Computable Document Format File | Wolfram Research CDF Player | Wolfram Research |
| .CDI | Intex Solutions, Inc. | Arquivos de dados | INTEX DealMaker Output | DealMaker | Intex Solutions, Inc. |
| .CDIC | Unknown Developer | Arquivos de dados | ConlangDictionary File | ConlangDictionary | Unknown Developer |
| .CDP | Trainz portal | Arquivos de dados | Trainz Simulator Content Dispatcher Pack | N3V Games Trainz Simulator | Trainz portal |
| .CDPX | CS Odessa | Arquivos de dados | ConceptDraw PROJECT XML File | CS Odessa ConceptDraw PROJECT | CS Odessa |
| .CDPZ | CS Odessa | Arquivos de dados | ConceptDraw PROJECT Document | CS Odessa ConceptDraw PROJECT | CS Odessa |
| .CDR | Corel | Arquivos de dados | CorelDRAW Vector Image File | Adobe Illustrator CC | Adobe Systems Incorporated |
| .CDS | CS Odessa | Arquivos de dados | ConceptDraw SlideShow | ConceptDraw PRO | CS Odessa |
| .CDV | Square Box Systems | Arquivos de dados | CatDV Catalog | CatDV | Square Box Systems |
| .CDW | ASCON | Arquivos de dados | KOMPAS Document | ASCON KOMPAS-3D | ASCON |
| .CDX | Microsoft Corporation | Arquivos de dados | Compound Index File | Microsoft Visual FoxPro | Microsoft Corporation |
| .CDXML | PerkinElmer | Arquivos de dados | ChemDraw XML File | Open Babel | Open Babel development team |
| .CDY | Prof. Dr. Ulrich Kortenkamp | Arquivos de dados | Cinderella Construction File | Cinderella | Prof. Dr. Ulrich Kortenkamp |
| .CED | JVCKenwood Group | Arquivos de dados | JVC Camera Video Data File | Unknown Software | Unknown Developer |
| .CEF | Richard Stott | Arquivos de dados | Class Action Gradebook Elementary File | Class Action Gradebook "Elementary Edition" | Richard Stott |
| .CEL | Affymetrix | Arquivos de dados | Affymetrix Probe Results File | The MathWorks MATLAB | MathWorks |
| .CEN | European Committee for Standardization | Arquivos de dados | CEN EN 13032 Photometric Data | Unknown Software | Unknown Developer |
| .CERT | AOL | Arquivos de dados | Netscape Certificate Index | Netscape Navigator | NetScape |
| .CF | Proofpoint, Inc. | Arquivos de dados | Sendmail Configuration File | Apache OpenOffice | Apache Software Foundation |
| .CF1 | Würth Online World GmbH | Arquivos de dados | WOW! Data | WOW! | Würth Online World GmbH |
| .CF4 | Equi 4 Software | Arquivos de dados | Catfish File Manager Support File | CatFish | Equi 4 Software |
| .CFA | Frontline | Arquivos de dados | ComProbe Analyzer Capture File | Frontline ComProbe Analysis System | Frontline |
| .CFB | Microsoft Corporation | Arquivos de dados | Compound Binary File | Microsoft Visual Studio | Microsoft Corporation |
| .CFH | FieldComm Group | Arquivos de dados | Capabilities File For FOUNDATION Fieldbus HSE | Foundation Fieldbus | FieldComm Group |
| .CFL | Corel Corporation | Arquivos de dados | Corel Flow Flow Chart File | Corel WordPerfect | Corel |
| .CFU | Symantec Corporation | Arquivos de dados | Symantec Client Firewall Policy Data | Client Firewall | Symantec Corporation |
| .CFW | PerkinElmer | Arquivos de dados | ChemFinder Form | ChemBioFinder | PerkinElmer |
| .CFX | Flow-Cal, Inc. | Arquivos de dados | Flow-Cal Data File | FLOWCAL Enterprise | Flow-Cal, Inc. |
| .CGB | Unknown Developer | Arquivos de dados | Gameboy Color Data | Unknown Software | Unknown Developer |
| .CGD | Cricket Technology | Arquivos de dados | CricketGraph Data | CricketGraph | Cricket Technology |
| .CGT | Gold Parsing System Team | Arquivos de dados | Gold Parsing System Compiled Grammar Table File | GOLD | Gold Parsing System Team |
| .CHE | Procedimientos-Uno, S.L. | Arquivos de dados | CHwinEHE Project Files | CHwinEHE | Procedimientos-Uno, S.L. |
| .CHECK | Open Source | Arquivos de dados | CASTEP Check Binary Data | CASTEP | Open Source |
| .CHG | Quicken | Arquivos de dados | Quicken Online Data File | Intuit Quicken | Quicken |
| .CHI | Microsoft Corporation | Arquivos de dados | Microsoft Help File Index | Microsoft Visual FoxPro | Microsoft Corporation |
| .CHK | Sophos | Arquivos de dados | InterCheck Checksum Database | Sophos | Sophos |
| .CHL | Leadtek Research | Arquivos de dados | WinFast PVR2 Channel List | Leadtek Research WinFast PVR2 | Leadtek Research |
| .CHM | Microsoft Corporation | Arquivos de dados | Compiled HTML Help File | Mozilla Firefox | Mozilla |
| .CHN | Qualis Research Associates | Arquivos de dados | Ethnograph Data | Qualis Research Associates Ethnograph | Qualis Research Associates |
| .CHP | Corel Corporation | Arquivos de dados | Ventura Publisher Chapter Document | Ventura Publisher | Corel |
| .CI3 | Lawtech (Aust.) Pty Ltd | Arquivos de dados | Calin Lawyer's Interest Calculator Data File | Calin Lawyer's Interest Calculator | Lawtech (Aust.) Pty Ltd |
| .CIB | DIAL | Arquivos de dados | DIALux Luminaire Data | ReluxSuite | Relux |
| .CIE | OxyTech | Arquivos de dados | CIE File Format File-Color Information | LITESTAR 4D Photoview | OxyTech |
| .CIF | Corel | Arquivos de dados | Easy CD Creator Disk Image | IsoBuster | Smart Projects |
| .CIG | Fifth Generation Systems | Arquivos de dados | Fastback Plus Compressed Backup | FastBack Plus | Fifth Generation Systems |
| .CII | Intergraph Corporation | Arquivos de dados | Caesar II Data | CAESAR II | Intergraph Corporation |
| .CIK | Corel | Arquivos de dados | Corel Graphics 10 Custom Dual Tone File | CorelDRAW Graphics Suite | Corel |
| .CIL | Symantec Corporation | Arquivos de dados | Norton CleanSweep Installation Log File | Microsoft Notepad | Microsoft Corporation |
| .CIN | Kodak | Arquivos de dados | Kodak Cineon Bitmap File | Adobe SpeedGrade | Adobe Systems Incorporated |
| .CITY | Unknown Developer | Arquivos de dados | Unknown Apple II File. (found On Golden Orchard Apple II CD Rom) | Atom | GitHub, Inc. |
| .CIX | IBM | Arquivos de dados | Rational XDE | Rational XDE | IBM |
| .CKL | DISA (Defense Information Systems Agency) | Arquivos de dados | DISA STIG Checklist | STIG (Security Technical Implementation Guides) | DISA (Defense Information Systems Agency) |
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