| .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 |
File extensions are not normally displayed to users. To change this, go to Control Panel, select Appearance and Personalization and Folder Options. Next, select the View and find the option "Hide extensions for known file types". The option should be deselected (cleared) and confirmed with OK.
