| .c | C/C++main Source Code File Format |
| .c# | Microsoft Visual C# |
| .c++ | C++ Source Code |
| .c-- | Sphinx C-- Language Source Code |
| .c-map | C-map |
| .c00 | Split Multi-volume ACE Compressed File Archive |
| .c01 | Split Multi-volume ACE Compressed File Archive |
| .c02 | Split Multi-volume ACE Compressed File Archive |
| .c03 | Split Multi-volume ACE Compressed File Archive |
| .c04 | Split Multi-volume ACE Compressed File Archive |
| .c05 | Split Multi-volume ACE Compressed File Archive |
| .c06 | Split Multi-volume ACE Compressed File Archive |
| .c07 | Split Multi-volume ACE Compressed File Archive |
| .c08 | Split Multi-volume ACE Compressed File Archive |
| .c09 | Split Multi-volume ACE Compressed File Archive |
| .c1 | Pov-Ray For Windows 3.x Scenes Advanced Newltpot |
| .c10 | Split Multi-volume ACE Compressed File Archive |
| .c11 | CARE-S InfoWorks User Defined Pollutant Detail |
| .c16 | C16 Creatures 3/Docking Station Image |
| .c18 | Dassault Systemes Catia V4 Sequential |
| .c1s | Photo Cache |
| .c2 | Pov-Ray For Windows 3.x Scenes Advanced Newltpot |
| .c21 | CARE-S InfoWorks Defined Pollutant Detail |
| .c24 | Drive Image Ace |
| .c2c | CopyToDVD Project |
| .c2d | WinOnCD Image Format |
| .c2e | Chinese Dictionary Index |
| .c2k | Microsoft Project Holidays |
| .c2r | Microsoft Windows Media Center Click-to-record Format |
| .c2u | Texas Instruments CBL 2 Format |
| .c2v | WellSight Systems License Information |
| .c2w | WaterCAD |
| .c2x | WinOnCD |
| .c3 | Pov-Ray For Windows 3.1 Scenes Advanced Newltpot |
| .c32 | Split Multi-volume ACE Compressed File Archive |
| .c39 | Split Multi-volume ACE Compressed File Archive |
| .c3d | Coordinate 3D Format |
| .c3d1 | Chem3D Cartesian 1 Chemical Modeller |
| .c3d2 | Chem3D Cartesian 2 Chemical Modeller |
| .c3e | CYPE Related |
| .c3t | Chemical Template |
| .c3xml | Chem3D XML Format |
| .c3z | OpenQwaq 3D Model Format |
| .c4 | JEDMICS Bitmap Image Format |
| .c40 | Split Multi-volume ACE Compressed File Archive |
| .c41 | Split Multi-volume ACE Compressed File Archive |
| .c42 | Split Multi-volume ACE Compressed File Archive |
| .c43 | Split Multi-volume ACE Compressed File Archive |
| .c44 | Split Multi-volume ACE Compressed File Archive |
| .c45 | Split Multi-volume ACE Compressed File Archive |
| .c46 | Split Multi-volume ACE Compressed File Archive |
| .c47 | Split Multi-volume ACE Compressed File Archive |
| .c48 | Split Multi-volume ACE Compressed File Archive |
| .c49 | Split Multi-volume ACE Compressed File Archive |
| .c4d | CINEMA 4D File Format |
| .c4dupdate | Cinema 4D Update |
| .c4f | Clonk Game Round |
| .c4g | Clonk Game System |
| .c4k | Clonk Key Format |
| .c4p | CrossOver Software Installer Format |
| .c4s | Clonk Game Scenario |
| .c4u | OpenClonk Update System |
| .c4v | Clonk Game Video |
| .c50 | Split Multi-volume ACE Compressed File Archive |
| .c51 | Split Multi-volume ACE Compressed File Archive |
| .c52 | Split Multi-volume ACE Compressed File Archive |
| .c53 | Split Multi-volume ACE Compressed File Archive |
| .c54 | Split Multi-volume ACE Compressed File Archive |
| .c55 | Split Multi-volume ACE Compressed File Archive |
| .c6 | Organic 2D/3D Drafting & 3D Modelling |
| .c64 | Commodore 64 ROM Image |
| .c85 | RISC OS JPEG Bitmap Image |
| .ca | Telnet Server Initial Cache Data Format |
| .ca1 | Delphi Install Disk |
| .ca2 | Delphi Install Disk12 |
| .ca4 | Delphi Installation |
| .ca5 | Delphi Installation |
| .caa | CleanApp Archive Format |
| .cab | Windows Cabinet Compressed Archive |
| .cabal | Haskell Cabal |
| .cac | DBASE IV Executable |
| .cache | Generally Cache Format |
| .cache-2 | VLC Media Player Font Cache |
| .cache-3 | VLC Media Player Font Cache |
| .cache2 | Pro/ENGINEER |
| .caction | Apple Mac OS X Automator Conversion Action Format |
| .cad | CAD Drawing Format |
| .cadc | Corpatla Baudadministration Data Format |
| .cadrg | Compressed ARC Raster Graphic |
| .cae | Abaqus CAE Model |
| .caf | Apple Core Audio Format |
| .caff | Apple Core Audio Format |
| .cag | Microsoft Clip Gallery Catalog Format |
| .cah | Ulead Photo Explorer Thumbnail Cache |
| .cai | SeeYou Flight Data |
| .caj | China Academic Journals Full-text Database |
| .cakewalkwindowlayout | Cakewalk Window Layout |
| .cal | CALS Raster Image Format |
| .calb | Coolect Album Format |
| .calibre | Calibre Device Data Format |
| .calibz | Chief Architect Symbol |
| .cals | CALS Raster Group 1 Image Format |
| .calx | Calendar Printing Assistant Template |
| .cam | Casio QV Digital CAMera Image Format |
| .camm | Espresso Mind Map Mind Map Format |
| .camp | WCS CAMP |
| .camproj | Camtasia Studio Project Format |
| .camrec | Camtasia Studio Recorder Format |
| .camthtr | Camtasia Studio Theater |
| .camv | Camtasia Screencast Video Format |
| .can | Canon Navigator Fax Format |
| .canf | CanOpener |
| .canim | Shank Game |
| .cannedsearch | Apple Mac OS X Finder Predefined Search |
| .caos | CanOpener Preference |
| .cap | PacketView Pro Packet Trace Data Format |
| .capfile | Ruby Capistrano Instruction |
| .caproj | Construct Game Project Format |
| .caps | CaptureSaver |
| .capx | Construct Game Project Archive Format |
| .car | Biosym Chemical Modeller Input Format |
| .carb | Apple Mac OS X Carbon Package |
| .carc | Nintendo DS Compressed Archive Format |
| .card | Funkiball Adventure |
| .caro | Adobe Acrobat Creatorcode |
| .cas | Autodesk AutoCAD License Format |
| .cascii | CACTVS Chemical ASCII Format |
| .case | SlipCover For Mac Template Format |
| .cat | Microsoft Security Catalog Format |
| .cat4d | Cinema 4D Catalog |
| .catalog | CATIA Catalog |
| .CATAnalysis | CATIA Analysis |
| .CATDrawing | CATIA Drawing |
| .CATfct | CATIA CATfct |
| .CATKnowledge | CATIA CATKnowledge |
| .CATMaterial | CATIA CATMaterial |
| .catom | Chief Architect Catalogue |
| .catpart | CATIA Part Format |
| .catpreferences | CATIA Preferences |
| .CATProcess | CATIA Process |
| .catproduct | CATIA Product Format |
| .CATRaster | CATIA Raster |
| .CATResource | CATIA Resource |
| .CATSettings | CATIA Settings |
| .CATShape | CATIA Shape |
| .CATSwl | CATIA CATSwl |
| .CATSystem | CATIA Functional Systems |
| .cav | Comodo Virus Definitions Format |
| .cawr | Espresso Workreport Format |
| .cax | VCollab 3D Model |
| .cb | Microsoft Clean Boot |
| .cb1 | CARE-S InfoWorks Biochemical Oxygen Detail |
| .cb4 | Actuate Analytics |
| .cb7 | CDisplay 7-Zip Comic Book Format |
| .cba | CDisplay ACE Comic Book Format |
| .cbb | ChessBase Search Booster |
| .cbc | Comic Book Collection |
| .cbcp | CodeBaby Production Studio Character Package |
| .cbd | Corel WordPerfect Dictionary |
| .cbds | Comic Book DS Format |
| .cbf | ChessBase Game Information Format |
| .cbg | CyberGauge Data Format |
| .cbh | ChessBase Chess Database Format |
| .cbk | Backup Configuration Format |
| .cbl | Cobol Language Source Code Format |
| .cbm | Bitmap Image Format |
| .cbmv | Comic Book Millennium Collection |
| .cbn | PaperMaster Cabinet |
| .cbo | Microsoft Interactive Training |
| .cbp | Code::Blocks Project Format |
| .cbplugin | Code::Blocks Plugin |
| .cbproj | C++ Builder Project |
| .cbq | StarOS Script |
| .cbr | Comic Book Archive Format Or ComicBook Reader Format |
| .cbs | Comodo Backup Script Format |
| .cbt | CDisplay TAR Comic Book Format |
| .cbu | Comodo Backup Backup Format |
| .cbv | ChessBase Archive Format |
| .cbw | ComicRack Webcomics |
| .cbx | Rational XDE |
| .cbxml | CodeBox XML Library |
| .cbz | Comic Book Archive Format Or ComicBook Reader Format |
| .cc | C++ Language Source Code Format |
| .cc1 | Briggs Softworks Calendar Commander |
| .cca | CC: MAil Data Format |
| .ccb | Visual Basic Animated Button Configuration |
| .ccbjs | CopperCube JavaScript Scene |
| .ccc | Microsoft Internet Chat Conversation Log |
| .ccd | CloneCD Track Description Format |
| .cce | Calendar Creator 2 Event |
| .ccf | CryptLoad Container Format |
| .ccgame | Microsoft XNA Game Studio Game Package Format |
| .cch | Photomodeler Photochip Thumbnail Format |
| .ccip | Curse Client 4 Addon Download Protocol Format |
| .ccj | Crossword Compiler Compiled Crossword Applet |
| .cck | Corel Clipart |
| .ccl | CCTools Levelset |
| .ccm | Multimedia Fusion Custom Menu |
| .ccn | Multimedia Fusion Development Format |
| .cco | Apple Cocoa |
| .ccp | CloneCD Profiles Format |
| .ccr | HealthFrame ASTM Continuity Of Care Record Format |
| .ccrf | Calcomp Raster Bitmap Image |
| .ccs | TrialDirector Clip Script Format |
| .ccscc | ClearCase Source Control Info Format |
| .cct | Macromedia (Adobe) Director Shockwave Cast Format |
| .ccw | Crossword Compiler Saved Puzzle |
| .ccwsln | Connected Components Workbench |
| .ccx | Click & Create Extension |
| .ccxml | Call Control EXtensible Markup Language |
| .cd | ClassDiagram Format |
| .cd2 | DATAIR Cafeteria Document System Custom Text |
| .cd5 | Chasys Draw Image |
| .cda | CD Audio Track |
| .cdata | Command & Conquer 3 Audio |
| .cdb | Windows Mobile Pocket Access Database Format |
| .cdc | Autodesk AutoCAD DesignCenter Preview Cache Format |
| .cdd | ConceptDraw Drawing Diagram Format |
| .cdda | Apple ITunes AIFF Audio Format |
| .cddx | Circuit Diagram Diagram Format |
| .cde | CADKEY Dynamic Extension |
| .cdem | CompeGPS Land Landscape |
| .cdf | Cyberspace Description Format |
| .cdf-ms | ClickOnce Deployment Binary Manifest Format |
| .cdfx | Cindex |
| .cdg | DART Karaoke Studio Lyrics Format |
| .cdi | DiscJuggler Image Format |
| .cdj | DiscJuggler CD-ROM Data |
| .cdk | Calamus SL Document |
| .cdl | CADKey CAD Language Format |
| .cdlx | Adobe Audition Audio CD Project Format |
| .cdm | NTI CD&DVD-Maker Image Format |
| .cdmedia | Boxer For Mac Cd-rom |
| .cdmm | ConceptDraw MINDMAP Document |
| .cdmp | WCS CDMP |
| .cdmt | ConceptDraw MINDMAP Template |
| .cdmtz | Compressed ConceptDraw MINDMAP Template |
| .cdmz | ConceptDraw MINDMAP Compressed Document Format |
| .cdo | Crescendo Music Score Format |
| .cdoc | DigiDoc Client Container |
| .cdp | Trainz Simulator Content Dispatcher Pack Format |
| .cdp2 | Trainz Classics Content Dispatcher Pack 2 Format |
| .cdpx | ConceptDraw PROJECT XML Format |
| .cdpz | ConceptDraw PROJECT Document |
| .cdr | CorelDRAW Vector Or Bitmap Format |
| .cdr3 | CorelDRAW 3 For Mac Vector Or Bitmap Image |
| .cdr4 | CorelDRAW 4 For Mac Vector Or Bitmap Image |
| .cdr5 | CorelDRAW 5 For Mac Vector Or Bitmap Image |
| .cdr6 | CorelDRAW 6 For Mac Vector Or Bitmap Image |
| .cdrw | CorelDRAW For Mac |
| .cdrx | Bosch Crash Data Retrieval Data Format |
| .CDRZIP | DICOM Compressed Image |
| .cds | ChemDraw Stationery Document |
| .cdsg | DrawMusic Chord Song |
| .cdt | CorelDRAW Template Format |
| .cdt6 | CorelDRAW 6 For Mac Template |
| .cdt_ | CorelDRAW For Mac Template |
| .cdu | CDU Paint Image Format |
| .cdv | CatDV Catalog |
| .cdw | KOMPAS CAD Drawing Format |
| .cdx | CorelDRAW Compressed Drawing Format |
| .cdxml | ChemDraw XML Format |
| .cdz | ROM With A View Project Format |
| .ce | Digital Vision ComputerEyes IFF Bitmap Format |
| .ce0 | Winewar Worm |
| .ce1 | Computer Eyes Raw Image Format |
| .ce2 | Computer Eyes Raw Image Format |
| .cea | DAZ 3D Carrara Pro Export |
| .ceb | Apabi EBook Format |
| .ced | JVC Corrupted Video Format |
| .cedata | Pogoplug |
| .cedprj | Ashampoo CoverEditor Cover Project Format |
| .cef | CenturionMail Format |
| .cei | CRiSP Harvest |
| .ceimg | CeRegEditor Registry Image |
| .cel | Lumena CEL Bitmap Image Format |
| .cell | CASTEP Supercell Material Data |
| .celtx | Celtx Project Format |
| .celx | Celestia Script |
| .cem | Empire Earth Game Format |
| .ceo | Winewar Worm |
| .cer | Internet Security Certificate |
| .cert | Netscape Certificate Index |
| .certauthorityconfig | Apple Mac OS X Certificate Assistant Configuration |
| .certsigningrequest | Apple Mac OS X Certificate Assistant |
| .cet | Hitachi Cobol |
| .cetrainer | DBVM |
| .cex | SolidWorks Enterprise PDM Vault Export Format |
| .cf | Sendmail Configuration Format |
| .cf2 | Common File Format 2 |
| .cf5 | DocuWare |
| .cf7 | Toshiba ConfigFree Profile Handling Module |
| .cfa | Adobe Premiere Pro Audio Format |
| .cfb | Disk Drill Recovered |
| .cfc | Adobe ColdFusion Component Format |
| .cfd | CryptoForge Document |
| .cfdi | Comprobante Fiscal Digital Por Internet |
| .cfe | CryptoForge Encrypted |
| .cff | ColorImpact Color Formula Format |
| .cff2 | Kodak Pandora Exported |
| .cfg | Configuration Files |
| .cfge | Jewel Quest Configuration Format |
| .cfi | CleverForm Script |
| .cfk | Microsoft Developer Studio Diagram |
| .cfl | IMVU Product Format |
| .cfm | Adobe ColdFusion Template Format |
| .cfml | Adobe ColdFusion Markup Language Format |
| .cfn | Calamus Font Data |
| .cfo | Turbo C Utilities C Form Object |
| .cfp | Bitmap Native Format For CoverFactory |
| .cfpreset | SA Color Finesse Plugin For Adobe After Effects |
| .cfr | Cross Fire Replay Format |
| .CFReplay | Crossfire Europe Replay |
| .cfs | INMOS Configuration Format |
| .cft | CFast Graphics |
| .cfw | ChemFinder Form |
| .cfx | Magix Movie Edit Pro |
| .cfxr | Cocoa Sfxr Format |
| .cfxxe | Possibly Malware |
| .cfz | Compressed Archive |
| .cg | NVidia CgFX Format |
| .cg3 | Cabri 3D Document |
| .cg4 | CALS Group IV Bitmap Graphics |
| .cga | Ventura Publisher CGA Display Font |
| .cgd | CricketGraph Data |
| .cgdb | Microsoft Clip Art Package |
| .cgf | Asm Objasm Format |
| .cgfx | CgFX Shader Format |
| .cgi | Common Gateway Interface Script Format |
| .cginc | Unity Custom Shader Include |
| .cgk | BlueSoleil |
| .cgm | Computer Graphics Metafile |
| .cgmap | CityGuide Region Map |
| .cgo | Railroad Tycoon 3 Car Properties |
| .cgp | PixelCryptor Encrypted Format |
| .cgr | CATIA MultiCAx Plug-in Conversion Format |
| .cgrp | Pro Tools Clip Group Format |
| .cgt | Gold Parsing System Compiled Grammar Table |
| .cgvp | NVidia Cg Programming Language XML |
| .cgx | ARM RL-TCPnet HTTP Web Server XML Web Page Update Script |
| .cgz | AssaultCube Map Format |
| .ch | OS/2 Configuration |
| .ch1 | IBM Freelance Graphics Chart |
| .ch10 | Irig 106 Original Recording |
| .ch3 | Harvard Graphics V3.0 Chart/image Format |
| .ch4 | WSxM |
| .ch5 | VisIt |
| .cha | Online Chat Configuration Format |
| .cham | Compiled HAM Format |
| .chap | MP4 Movie Chapter |
| .charmm | CHARMm Chemical Modeller Input |
| .charset | Character Set Format |
| .chart | Feedback Chart Format |
| .chat | Online Chat Configuration Format |
| .chatlog | Adium Chat Log |
| .chc | HCFR Colorimeter Data Format |
| .chd | MAME Compressed Hard Disk Format |
| .che | CHwinEHE Project |
| .chef | Chef Source Code Format |
| .chesstitanssave-ms | Chess Titans Save Game Format |
| .chf | PcAnywhere Remote Control |
| .chg | Quicken Online Data Format |
| .chh | C++ Header |
| .chi | Microsoft Help Index |
| .chj | IBM SPSS Interview Cache |
| .chk | ScanDisk File Fragment |
| .chkn | IMVU Create Mode Temporary |
| .chksplit | Incredible Bee Archiver Checksum |
| .chl | Microsoft Internet Explorer Channel Information Format |
| .chm | Microsoft Compiled HTML Help Format |
| .chml | Chameleon Encrypted Format |
| .chn | Ethnograph Data Format |
| .cho | Animation:Master Choreography |
| .chord | Song Chords Format |
| .chp | Ventura Publisher Chapter Document |
| .chq | Microsoft Help Combined Full-text Search |
| .chr | Borland Language Stroke Font Format |
| .chrparams | CryENGINE Character Paramters Format |
| .chs | Windows Chinese Noise-Word List Format |
| .cht | ZSNES Cheat Code Format |
| .chtml | Compact HTML Document |
| .chunk001 | File Splitter Split File (part 1) |
| .chv | ChView Star Map Format |
| .chw | Microsoft Help HTML Help General Index Format |
| .chx | Autodesk AutoCAD Standards Check Format |
| .ci | CitectSCADA Format |
| .cid | CoDiagnostiX User Defined Implant |
| .cidb | Apple ITunes CD Information Format |
| .cif | Easy CD Creator CD Image Format |
| .cii | Caesar II |
| .cik | Corel Graphics 10 Custom Dual Tone |
| .cil | Microsoft Office Clip Gallery Download Package |
| .cim | CimPack Design Drawing |
| .cimg | CImg Image Format |
| .cin | Kodak Cineon Image Format |
| .cin96lm | Microsoft Cinemania |
| .cin96upd | Microsoft Cinemania Format |
| .cine | Vision Research Phantom Cine Camera Video Format |
| .cinema4D | Cinema 4D For Amiga |
| .cio | SWAT Master Watershed |
| .cip | CryptoBuddy Encrypted Format |
| .cipo | Cartesian Products Compressed Internet Document |
| .cir | Supermax ECAD Command Save |
| .circ | Logisim Circuit |
| .circuit | KTechlab Circuit Design Format |
| .cis | CheckInbox |
| .ciso | Wii Compressed Game Image |
| .cit | Intergraph Scanned Image |
| .civ | Empire Earth Custom Civilization Information |
| .civ5map | Civilization 5 Map |
| .civ5save | Civilization 5 Saved Game Format |
| .ciw | Web Of Science Export |
| .cix | Rational XDE |
| .cjstyles | Skin Builder Project |
| .ck1 | Commander Keen 1 Game Data |
| .ck2 | Commander Keen 2 Game Data |
| .ck3 | Commander Keen 3 Game Data |
| .ck4 | Commander Keen 4 Game Data |
| .ck5 | Commander Keen 5 Game Data |
| .ck6 | Commander Keen 6 Game Data |
| .cka | Comfort Keys Database |
| .ckb | Cricket Audio Sound Bank Format |
| .ckbx | Cricket Audio XML Bank Description Format |
| .ckd | CADKEY Design Format |
| .ckf | Casio Keyboard Audio Format |
| .ckp | Ingres Database Checkpoint Data |
| .cks | Microsoft Windows CE Image Info |
| .ckt | B2 Spice Circuit Design Format |
| .ckz | QuickSFV File Verification Database |
| .cl | IconUtils Mouse Cursor Library Format |
| .cl2 | HY-TEK Meet Results Format |
| .cl2arc | Comic Life 2 Document Archive Format |
| .cl2doc | Comic Life 2 Document Format |
| .cl2lyt | Comic Life 2 Layout Format |
| .cl2tpl | Comic Life 2 Template Format |
| .cl3 | Easy CD Creator CD Layout |
| .cl4 | Easy CD Creator CD Layout Format |
| .cl5 | Easy CD Creator Saved Project Format |
| .cla | Clarion For DOS Source Code |
| .claf | Claris Font |
| .clam | Adobe InDesign Dictionary |
| .clarify | Blue Mango Clarify Document Format |
| .clas | Java Class |
| .class | Java Bytecode Class Format |
| .classdiagram | Microsoft Visual Studio Class Diagram |
| .classlist | SMART Notebook Class List Format |
| .classpath | Eclipse IDE JAVA Project Related |
| .clb | Super NoteTab ClipBook Template Format |
| .clbx | MP3 Automagic CD Cover Creator Label |
| .clc | Microsoft Schedule+ 7 Habits Mission Statement |
| .cld | Canon CD-Label Print Label Layout Format |
| .cldcvt | CD-LabelPrint Converted Data |
| .cldlyr | TerraGen Cloud Layer |
| .cle | Icon Lock-iT Locked File Indicator |
| .cleo | Grand Theft Auto Vice City Mod Format |
| .clf | ListPro |
| .clg | QIP List Of Ignored Contacts Format |
| .clgx | Collage Maker Collage |
| .cli | Client Management System Customer |
| .clipping | Apple Mac OS X Finder |
| .clips | Coda For Mac Clips Format |
| .clix | CLIX Command Format |
| .clj | Clojure Source Code |
| .clk | CorelDRAW Corel R.A.V.E. Animation Format |
| .clkk | Clicker Keyboard Format |
| .clkt | Clicker Template Format |
| .clkw | Clicker Word Bank Format |
| .clkx | Clicker Grid Set Format |
| .cll | Crick Software Clicker |
| .clm | Micrografx Picture Publisher Macro Format |
| .cln | Microsoft Windows 3.x Configuration Backup |
| .clo | Cloe Ray-Tracer Image |
| .cloe | Cloe Ray-Tracer Image |
| .cloud | GOM Atos Scanner |
| .clp | Microsoft Windows Clipboard Format |
| .clpi | Blu-Ray Clip AV Stream Format |
| .clpprj | CodeLobster PHP Edition Project |
| .clr | Adobe Flash Color Table Format |
| .clr0 | Nintendo Wii Color Swapping Animation |
| .cls | JavaScript Class Definition Format |
| .clt | VisualBoyAdvance Cheat List Format |
| .clu | Broken Sword 2 Dialogue |
| .clv | QIP Visible List |
| .clw | Microsoft Visual C++ MFC Class Wizard Information Format |
| .clx | Adobe Standard Dictionary Format |
| .cly | CorelDRAW Custom Layout |
| .clz | Tomb Raider: The Angel Of Darkness Game |
| .cm | Grand Theft Auto CLEO Custom Mission Format |
| .cm10 | CaseMap Case Format |
| .cm2 | Poser Camera Set Format |
| .cm3 | CaseMap Data |
| .cm4 | ClipMate Data |
| .cm5 | LexisNexis Case Analysis |
| .cm8 | CaseMap Case |
| .cma | Applix TM1 Database Format |
| .cmake | CMake Module |
| .cmap | CmapTools Concept Map Format |
| .cmb | Xtree For Windows Button Bar |
| .cmbl | Logger Pro Data Format |
| .cmc | Comic Collector Collection Data |
| .cmd | Microsoft Windows Command Script Format |
| .cmdb | ANSYS CFX Mesh Database |
| .cmdf | CrystalMaker Data |
| .cmdt | Claris Dictionary |
| .cme | Crazy Machines Level Format |
| .cmf | Creative Labs FM-synthesis Music Format |
| .cmg | ChessMaster Saved Game |
| .cmi | The Dig Bundle |
| .cml | Chemical Markup Language Document Format |
| .cmm | Corel Multimedia Manager Album Format |
| .cmmcd | Camtasia Studio MenuMaker Project |
| .cmmp | Camtasia MenuMaker Project |
| .cmmtheme | CleanMyMac Theme Format |
| .cmmtpl | Camtasia MenuMaker Template |
| .cmn | Systems Management Server (SMS) Update |
| .cmo | Spanish Whiz Sound |
| .cmod | Celestia Model Format |
| .cmp | PKWare Compression Library Archive Format |
| .cmproj | Camtasia For Mac Project Format |
| .cmp_xml | Solid Edge XML Design |
| .cmr | Coach Saved Results |
| .cmrbk | CaseMap ReportBook Definition |
| .cmrec | Camtasia For Mac Record Format |
| .cms | CaseMap Case Script Format |
| .cmt | Chinon ES-1000 Digital Camera Image Format |
| .cmtx | E-Sword Commentary |
| .cmu | CMU Window Manager Bitmap Image |
| .cmv | CorelDRAW CorelMove Animation |
| .cmw | Microsoft Office Custom Maintenance Wizard Data |
| .cmx | Corel Presentation Exchange Format |
| .cmy | CorelDraw Custom |
| .cmz | Poser Compressed Camera Set Format |
| .cn | CNwin/MLwin Account |
| .cn1 | CNR Modem Initialization Data Format |
| .cn3 | CN3D |
| .cna | Catena Project Format |
| .cnb | Pegasus Mail Noticeboard Mail Stored Message |
| .cnc | CNC Machine Tool Path Format |
| .CNC3Campaign | Command And Conquer 3 Campaign Save Game |
| .cnd | Melco Condensed Embroidery Format |
| .cndx | Avery DesignPro For Mac Label Format |
| .cnf | Network Configuration Format |
| .cng | CryptoNG Encrypted Format |
| .cni | CWBench |
| .cnk | Microsoft Dynamics GP Chunk |
| .cnm | NoteMap Outline Format |
| .cnn | ADO-network Connection Configuration |
| .cno | INet-Server Error Description |
| .cnq | WebShop Platinum Project |
| .cnr | Pegasus Mail Mail Message Stored In Systemwide Folder |
| .cns | Windows 2000 Client Connection Manager Export Format |
| .cnt | Help Contents Format |
| .cntk | Microsoft Outlook Express Contact |
| .cntl | GoCart Control |
| .cnv | Canvas Drawing Format |
| .cnx | Pegasus Mail |
| .co | Cobalt 3D |
| .coa | Caligari TrueSpace 3D Object |
| .cob | COBOL Programming Language Source Format |
| .coc | Bibexcel |
| .cod | Blackberry Compiled Java Code |
| .codaplugin | Coda For Mac Plugin Format |
| .codasite | Coda For Mac Web Project Format |
| .coe | Xilinx BRAM Initialization |
| .cof | AutoDesk Data Format |
| .coffee | CoffeeScript Script Format |
| .cok | INet-Server Error Report |
| .col | Autodesk Colour Palette |
| .collection | Adobe Bridge Collection Format |
| .collisionmesh | Battlefield Collision Mesh |
| .colloquytranscript | Colloquy Chat Transcript |
| .color | Amaya Config |
| .colorpicker | Apple Mac OS X Color Picker Component |
| .colors | SAM Makelogo Color |
| .colourscheme | J&ASoft Speedy Browser Color Scheme Settings |
| .colr | Kaleidoscope Scheme |
| .colz | Adobe Collage Moodboard Format |
| .com | Command Executable Format |
| .comfycakessave-ms | Comfy Cakes Saved Game Format |
| .comicdoc | Comic Life Document Format |
| .command | Apple Mac OS X Terminal Format |
| .commanderDoc | Apple Qmaster |
| .common | Unix Script |
| .comp | CodeWarrior Compiler |
| .comparison | Merge Comparison Report |
| .complete | SendSafe Deciphered E-message |
| .compo | DAZ 3D Carrara Pro 7 Or 8 Temporary |
| .component | Mac OS X System Component |
| .componentdiagram | Microsoft Visual Studio Component Diagram |
| .components | Mac OS X System |
| .compositefont | Composite Font Format |
| .compositionmodel | Invantive Composition Data Model |
| .compress | Microsoft Compress |
| .compressed | WordCompress Compacted Web Format |
| .con | Corel WordPerfect Concordance Format |
| .conf | Configuration Information Format |
| .config | Configuration Format |
| .configprofile | Apple Configuration Profile |
| .configure | Bash |
| .confluence | Eclipse Mylyn WikiText Confluence |
| .conform | Conformalizer Change List Format |
| .console | Widows NT Console |
| .cont | Panasonic Camcorder Extra |
| .contact | Microsoft Windows Contact Format |
| .contentproj | XNA Game Studio Game Content Project |
| .contents | MAC OS X |
| .contentsofclipboard | WinXP Powertoy |
| .contour | Contour Screenplay Format |
| .controls | OpenBVE Keyboard Settings Format |
| .converterx | SiMX TextConverter Project |
| .coo | AutoCAD Bounding Coordinates Cookie |
| .cook | Netscape For Mac Cookie |
| .cool | QB - Text Analyzer Vocabulary List |
| .coords | Ribbons Coords |
| .cop | Sam Coupé Sound |
| .copreset | Capture One Preset Format |
| .copy | Sony Ericsson Protected Content Format |
| .cor | CorelDRAW Format |
| .cos | Creatures Source Code Format |
| .cos2 | Pinnacle Studio Cache Format |
| .costyle | Capture One Style Format |
| .counter | Netobjects Fusion Components Bbscomp Message |
| .cov | Microsoft Cover Page Editor Fax Cover Page Format |
| .coverage | Microsoft Visual Studio Code Coverage |
| .coveragexml | Microsoft Visual Studio Code Coverage |
| .cow | Thief Game |
| .cox | Click & Create Extension |
| .cp | Xcode C++ Source Code Format |
| .cp1 | CARE-S InfoWorks Phosphorus Detail |
| .cp2 | ChessBase Theme Classification |
| .cp3 | Grand Prix 3 Cockpit Shape Format |
| .cp8 | CP8 256 Gray Scale Image |
| .cp9 | ChoicePoint Encrypted Format |
| .cp? | LoseThos C+ Source |
| .cpa | Adobe Premiere Conformed Audio Format |
| .cpb | Comicino Studio Project Format |
| .cpbitmap | Apple IPhone Bitmap Wallpaper Format |
| .cpc | Cartesian Perceptual Compression Compressed Image |
| .cpct | Compact Pro Archive |
| .cpd | CorelDRAW Corel PrintOffice Drawing Format |
| .cpdt | Adobe Captivate Design Template |
| .cpe | Win95 Cover Page Editor Fax Cover Sheet Format |
| .cpf | Cognos Project Format |
| .cpg | Manga Studio Drawing |
| .cpgz | Compressed UNIX CPIO Archive |
| .cph | Corel Print House Printing Project Format |
| .cpi | AVCHD Clip Information Format |
| .cpio | Unix CPIO Archive Format |
| .cpk | DTM Test Log Format |
| .cpl | Microsoft Windows Control Panel Format |
| .cpmz | Miradi Project Format |
| .cpn | Age Of Empires Campaign Format |
| .cpo | Corel Print House Data |
| .cpp | C++ Main Source Code File Format |
| .cpq | Compaq OEM Disc Configuration Format |
| .cpr | Cubase Project Format |
| .cprr | Adobe Captivate XML Script |
| .cps | Corel Photo House Image Format |
| .cpt | Corel PHOTO-PAINT Bitmap Format |
| .cpt2 | M-Tron Pro Library |
| .cptl | Adobe Captivate Project Template Format |
| .cptm | Adobe Captivate Theme |
| .cptx | Adobe Captivate Project Format |
| .cpu | SiSoftware Sandra |
| .cpx | Oracle Application Development Framework ADF Binding Context Format |
| .cpy | ECopy Desktop Scanned Document Format |
| .cpz | LoseThos C+ Source |
| .cql | XDCC Catcher Queue List |
| .cqt | MAIL.DAT Container Quantity Data |
| .cr | CRiSP Source Code |
| .cr1 | LoggerNet CRBasic Source |
| .cr2 | Canon Digital Camera RAW Image Format Version 2.0 |
| .cr5 | Survey Pro Coordinate |
| .craft | KSP Spacecraft Format |
| .crash | Apple Mac OS X Console Report Format |
| .crashed | AbiWord Crash-saved Document Format |
| .crb | BigOven Recipe Database |
| .crc | Total Commander CRC Format |
| .crd | Microsoft Windows Cardfile Database Format |
| .crdownload | Google Chrome Incomplete Download Format |
| .crds | Microsoft Windows CardSpace Backup Format |
| .crec | Microsoft Lync 2010 Recording |
| .creole | Creole Source |
| .crev | Adobe Captivate Review Format |
| .crf | Enhanced Dark Engine Game Archive Format |
| .crg | Calamus Picture Image |
| .crh | EN-CC Truss Geometry |
| .cri | Crystal Reports |
| .crl | Certificate Revocation List |
| .crmlog | Microsoft Windows CRM Log |
| .crp | CorelDRAW Corel Presents Run-time Presentation |
| .crs | Corel WordPerfect Conversion Resource Format |
| .crs3 | OmniPage Lite |
| .crt | Internet Security Certificate |
| .crtr | MultiAd Creator Pro Document Format |
| .crtx | Microsoft Office 2007 Chart Template Format |
| .crv | CorelDRAW Corel PHOTO-PAINT 10 Custom Gradients Format |
| .crw | Canon Digital Camera RAW Image Format |
| .crwl | Microsoft Windows Crawl Format |
| .crx | Google Chrome Extension Installer File Format |
| .cry | CryENGINE Map Format |
| .crypt | WhatsApp Messenger Encrypted Message Database Backup |
| .crypt5 | WhatsApp Messenger Encrypted Message Database Backup |
| .crypt6 | WhatsApp Messenger Encrypted Message Database Backup |
| .crypt7 | WhatsApp Messenger Encrypted Message Database Backup |
| .crypted | Ashampoo WinOptimizer Encrypted Format |
| .cryptomite | CryptoMite Encrypted Archive |
| .cryptra | Cryptra Encrypted Format |
| .crysisjmsf | Crysis Saved Game Format |
| .crysispsf | Crysis Warhead Saved Game Position Format |
| .crz | Compressed Poser Character Rigging Format |
| .cs | Microsoft Visual Studio Visual C#.NET Source Format |
| .cs1 | Sinar CaptureShop |
| .cs2 | CyberStep2 |
| .cs4 | Sinar CaptureShop 4-shot Image |
| .cs8 | Unix Graphics Format |
| .csa | Agilent PNA Code Calset Format |
| .csac | Web Research Collection Optimization Temporary |
| .csaplan | SPSS Analysis Plan Format |
| .csassembly | ICQ 6 |
| .csattr | Microsoft Visual Studio Attractor |
| .csb | Corel PHOTO-PAINT Script |
| .csc | 18 Wheels Of Steel: Pedal To The Metal Game |
| .cscpkt | Sample Packet |
| .csd | Compact Shared Document |
| .csdproj | C# Device Project |
| .cse | Web Research Document Package |
| .csf | Adobe Photoshop Color Settings Format |
| .csgrad | Microsoft Visual Studio Gradients |
| .csh | Adobe Photoshop Shapes Format |
| .cshrc | UNIX Command |
| .cshtml | ASP.Net Web Page |
| .csi | ContentServ CS EMMS Suite Include Format |
| .csj | RIM CSJ Registration |
| .csk | Claris Works |
| .cskin | CD Art Display Skin Format |
| .csl | CineStyle Color Settings Format |
| .csm | 3ds Max Character Studio Maker Format |
| .csmanifest | ICQ 6 Settings |
| .csml | Chemical Style Markup Language |
| .csn | Adobe Dreamweaver Snippet Format |
| .cso | CISO Compressed ISO Format |
| .csom | Eudora For Mac |
| .csp | CorelDRAW Service Bureau Profiler Format |
| .csplan | SPSS Sampling Plan Format |
| .csproj | Microsoft Visual Studio Visual C# Project Format |
| .csq | Microsoft FoxPro Queries |
| .csr | Certificate Signing Request Format |
| .css | Cascading Style Sheets Format |
| .css1 | Cascading Style Sheet |
| .csstore | Apple Mac OS X Cache |
| .cst | Commonspace Document Format |
| .csv | Comma Separated Value Format |
| .csview | Microsoft Visual Studio Views |
| .csvx | XML CSV |
| .csw | Corel WordPerfect Setup Information |
| .csx | Microsoft Visual C# Primary Script Format |
| .csy | Canvas Symbol Library Format |
| .csz | The Core Media Player Skin |
| .ct | IRIS CT Image Format |
| .ct0 | Tajima TBF Condition |
| .ct1 | SMS Proposed Site Control |
| .ct7 | CaseMap Case Analysis Template |
| .ct8 | CaseMap Case Template |
| .cta | ColorTouch Assistant Settings |
| .ctb | AutoCAD Colour-dependent Plot Style Table Format |
| .ctbl | Xamine NSCL |
| .ctbodyfitting | CrazyTalk Animator Format |
| .ctc | SeeYou Flight Data |
| .ctd | Tomahawk Gold Compressed Tomahawk Document |
| .cte | Classical Text Editor Document |
| .ctf | AVG Antivirus Update Control Format |
| .ctfsys | OS X Mach Kernel System |
| .ctg | BMC Software PATROL Format |
| .cti | Collectorz.com Template Info |
| .ctit | RAR Archive |
| .ctk | TeKton3D Project |
| .ctl | Visual Basic Control File (Active X Control File) |
| .ctm | Crazy Talk Face Model Format |
| .ctmdpi | MRMC Markov Reward Model Checker Matrix |
| .ctn | Cadterns Sloper Format |
| .cto | Microsoft Visual Studio Binary Command Table Output |
| .ctp | CakePHP Template Format |
| .ctproject | CrazyTalk Animator Project |
| .ctr | BrainVoyager QX Contrast |
| .cts | CrazyTalk Audio Format |
| .ctsym | Microsoft Visual Studio Command Table Output |
| .ctt | Windows Live Messenger Contact List Format |
| .ctv | Citavi Project Format |
| .ctv3 | Citavi 3 Project Format |
| .ctx | Microsoft Windows Terminal Server INI Backup Format |
| .ctxt | BlueJ Information Format |
| .cty | SimCity City Format |
| .ctz | Custody Toolbox Compressed Backup |
| .cu | CUDA Source Code Format |
| .cu1 | Photoline 4 Curve |
| .cu3 | Photoline Curves Clut |
| .cu? | Photoline Clut |
| .cub | Windows Installer Validation Module Format |
| .cube | Antaeus |
| .cue | Cue Sheet Description Format |
| .cuf | Turbo C Utilities Form Definition |
| .cui | AutoCAD Customization Format |
| .cuix | Autodesk AutoCAD Custom User Interface Format |
| .cul | IconForge ImageForge Cursor Library |
| .cup | SeeYou Waypoint |
| .cur | Windows Cursor Format |
| .current | WhatsApp Messenger Encrypted Message Database |
| .cursemod | Curse Client Mod |
| .cursor | Sun Cursor |
| .cursorfx | CursorFX Cursor Theme Format |
| .curxptheme | CursorFX Theme Format |
| .cus | AutoCAD Custom Dictionary Format |
| .cust | QuarkXPress Mac File Type |
| .customdestinations-ms | Microsoft Windows 7 Jump List |
| .cut | Dr. Halo Bitmap Format |
| .cutecutproject | Cute Cut Project |
| .cuv | Origin Sample Curve |
| .cu_ | Microsoft Windows Winhelp Compressed |
| .cv | Microsoft CodeView Information Screen |
| .cv5 | Canvas 5 Drawing Format |
| .cva | HP Compaq Diagnostics Format |
| .cvc | CVideo Format |
| .cvd | Clam AntiVirus Database Format |
| .cvf | CPU-Z Validation Format |
| .cvg | Calamus Vector Image File Format |
| .cvi | CassiniVision Map Image Format |
| .cvm | Odin Sphere |
| .cvn | Sonic CineVision Encoding Session Format |
| .cvp | Portrait Image Format |
| .cvr | Microsoft Office Crash Report Format |
| .cvs | CVS And VMS Sound Files (continous Variable Slope) |
| .cvsignore | Eclipse CVS Settings |
| .cvsrc | TortoiseCVS CVS Command |
| .cvt | Canvas External Tool Format |
| .cvw | CaseView Document Format |
| .cvx | Canvas Drawing Format |
| .cvz | Card Vault Inventory |
| .cw | CardWorks Template Format |
| .cw3 | Claris Works Document |
| .cw7 | COMPRESS Related |
| .cwb | Cakewalk Bundle |
| .cwc | CADfix Wizard Configuration |
| .cwdb | ClarisWorks Database |
| .cwf | CorelDRAW Workspace Format |
| .cwgr | ClarisWorks Drawing |
| .cwie | CodeWarrior |
| .cwk | ClarisWorks Document Format |
| .cwks | ClarisWorks |
| .cwl | ClarisWorks Library |
| .cwlink | CodeWarrior |
| .cwm | WebSphere Map Designer Express Map Definition |
| .cwms | CompeGPS Land Remote Map |
| .cwp | Cakewalk Sonar Audio Project Format |
| .cwpt | ClarisWorks Painting Drawing |
| .cwr | Crystal Reports Report |
| .cws | ClarisWorks Template Format |
| .cwss | ClarisWorks Spreadsheet |
| .cwt | ClarisWorks Texture Format |
| .cww | Crossword Weaver Format |
| .cwwp | ClarisWorks Document |
| .cwx | Sonar Track Template |
| .cwz | Circuit Wizard Format |
| .cw_ | CorelDRAW Workspace |
| .cx | CodeMapper Script |
| .cx3 | CMS Video Format |
| .cxa | ANSYS Fluent Animation Metadata |
| .cxarchive | CrossOver Bottle |
| .cxb | Custody X Change Data |
| .cxd | SimplePCI Graphics Data Format |
| .cxe | Common XML Envelope |
| .cxf | Google Picasa Collage Format |
| .cxl | Business Integrator Extract Schema |
| .cxml | Microsoft Silverlight Server Side Data |
| .cxp | Omron CX Programmer Format |
| .cxq | SillyDl.CXQ Downloading Trojan |
| .cxr | CX-Programmer Settings |
| .cxt | Adobe Director Protected Cast Format |
| .cxv | Custody X Change Data |
| .cxx | C++ Main Source Code File Format |
| .cya | Cyana Macro |
| .cyberducklicense | Cyberduck For Mac OS License Format |
| .cyberduckprofile | Cyberduck Connection Profile |
| .cyi | Clustify Input Format |
| .cyl | Ribbons Cylinder |
| .cyo | Clustify Output Format |
| .cyp | Home Designer Pro Project Format |
| .cyr | Crysis Level |
| .cys | Clustify Summary Statistics Format |
| .cyw | Rbot.CYW Worm Format |
| .cz | Czech Language Translation |
| .czd | The Crash Zone Drawing Format |
| .czi | Carl Zeiss Image Data Format |
| .czip | ZG Encrypted Zip Archive |
| .czn | RMCProfile Atom List |
| .czp | ClozePro Archive Format |
| .c_ | Microsoft Winhelp Compressed |
| .c__ | C++ Source Code |
