| C | Site configuration for Secure Remote (CheckPoint VPN) |
| C-- | Sphinx C-- Source code |
| C00 | Ventura Publisher Print file |
| C01 | Typhoon wave |
| C86 | Computer Innovation (C86) Source code |
| CA | Telnet Server Initial cache data file |
| CAB | Microsoft cabinet file (program files compressed for software distribution) |
| CAC | dBase IV Executable file |
| CACHE | Shared Cache file |
| CAD | AutoCAD drawing database file |
| CAG | Catalog file (Microsoft Clip Gallery v. 2.x,3.x,4.x) |
| CAL | SuperCalc 4/5 Spreadsheet |
| CAM | Casio camera file |
| CAN | Navigator Fax |
| CAP | Compressed music file |
| CAR | AtHome assistant file |
| CAS | Comma-delimited ASCII file |
| CAT | dBase Catalogue file |
| CB | Microsoft clean boot file |
| CBC | CubiCalc Fuzzy Logic System file |
| CBF | Vietcong (game) Pterodon big file |
| CBI | Column binary file (used in IBM mainframe systems) |
| CBL | Cobol Source code |
| CBM | XLib Compiled Bitmap |
| CBR | Comic book or paperback RAR file (decompress with RAR utility) |
| CBT | Generic Computer based training file |
| CBZ | Comic book or paperback ZIP file (decompress with WinZip or similar program) |
| CC | C++ Source code |
| CC3 | Close Combat 3 file |
| CCA | cc:mail archive file |
| CCB | Visual Basic Animated Button configuration file |
| CCC | Curtain Call Native bitmap graphic |
| CCD | Elaborate Bytes Clone CD mapfile for creating and reading .img files |
| CCE | Data file (Calendar Creator Plus) |
| CCF | Symphony Communications Configuration file |
| CCH | Corel Chart |
| CCL | Intalk Communication Command Language |
| CCM | Lotus CC:Mail "box" file (for example, INBOX.CCM) |
| CCO | XBTX Graphics |
| CCT | Macromedia Director Shockwave cast file |
| CDA | CD Audio Track |
| CDB | CardScan Database (CardScan) |
| CDF | Netcdf Graphic file |
| CDFS | Compact Disk filing system |
| CDI | Phillips Compact Disk Interactive file |
| CDK | Atari Calamus Document |
| CDM | Visual dBASE custom data module |
| CDR | Raw Audio-CD data file |
| CDT | CorelDraw Data file |
| CDX | Microsoft's Visual Foxpro index |
| CE | The FarSide Computer Calendar Main CE file |
| CEF | Cruzer encrypted file (used to secure files on Cruzer USB flash drives) |
| CEG | Tempra Show Bitmap graphic |
| CEL | AutoDesk Animator Cel Image |
| CER | Certificate file (MIME x-x509-ca-cert) |
| CEX | Caddie Exchange file |
| CF | Imake Configurtion file |
| CFB | Comptons Multimedia file |
| CFG | Configuration file |
| CFL | CorelFLOW Chart |
| CFM | Visual dBASE Windows customer form |
| CFN | Atari Calamus Font data file |
| CFO | TCU Turbo C Utilities C form object |
| CFP | The Complete Fax Portable fax file |
| CGA | Ventura Publisher Display font file |
| CGI | Common gateway interface script |
| CGM | Computer Graphic Metafile |
| CH | Clipper 5 Header |
| CH3 | Harvard Graphics 3.0 Chart |
| CH4 | Charisma 4.0 Presentation |
| CHD | FontChameleon Font descriptor |
| CHF | pcAnywhere remote control file |
| CHI | ChiWriter Document |
| CHK | WordPerfect for Windows Temporary file |
| CHL | Configuration History Log |
| CHM | Compiled HTML file |
| CHN | Ethnograph Data file |
| CHP | Ventura Publisher Chapter file |
| CHR | Character Sets (Borland) |
| CHT | Harvard Graphics Vector file |
| CIF | Easy CD Creator image |
| CIL | Clip Gallery download package file |
| CIM | Sim City 2000 file |
| CIN | Kodak Cineon Bitmap file |
| CIX | TCU Turbo C Utilities Database Index |
| CK1 | iD/Apogee Commander Keen 1 data |
| CK2 | iD/Apogee Commander Keen 2 data |
| CK3 | iD/Apogee Commander Keen 3 data |
| CK4 | iD/Apogee Commander Keen 4 data |
| CK5 | iD/Apogee Commander Keen 5 data |
| CK6 | iD/Apogee Commander Keen 6 data |
| CKB | Borland C++ Keyboard mapping file |
| CKF | Casio Keyboard File |
| CL | Generic LISP Source code |
| CL3 | Layout file (Adaptec Easy CD Creator) |
| CLASS | Java class |
| CLC | TI-83 Plus Flash Debugger file |
| CLG | Windows Catalog file |
| CLL | Cricket Software Clicker File |
| CLO | Cloe Image |
| CLP | Quattro Pro Clip art |
| CLR | PhotStyler Color defintion |
| CLS | C++ Class Definition |
| CLX | Macro ToolsWorks Macro file |
| CM | Craftman Data |
| CMA | Database file in plain text format (APPLIX TM1) |
| CMD | DOS CP/M command file |
| CMF | Corel Metafile |
| CMG | Chessmaster saved game |
| CMK | Card Shop Plus file |
| CMM | CEnvi Batch file |
| CMP | Address document |
| CMR | MediaPlayer Movie |
| CMV | Corel Move animation |
| CMX | Corel Presentation Exchange image |
| CMYK | Raw cyan, magenta, yellow, and black bytes file |
| CNC | Click 'N Create General Program data |
| CNF | Configuration file used by Telnet, Windows, and other applications with varying internal formats |
| CNM | Windows application menu options and setup file |
| CNQ | Compuworks Design Shop file |
| CNT | Windows (or other) system content files for the help index and other purposes |
| CNV | WordPerfect for Windows Temporary file |
| CNV | Conversion files (WS_FTP Pro) files that will be converted from (Example) "HTML-"HTM" for upload |
| COB | COBOL Source code |
| COB | trueSpace 2 object |
| COD | FORTRAN Compiled code |
| COD | dBase Application Generator Template source file |
| COE | Xilinx coefficient |
| COL | Microsoft Multiplan Spreadsheet |
| COM | Command file (program) |
| CON | Simdir Configuration file |
| CP | CryptoPad.NET Encrypted document |
| CP8 | CP8 256 Gray Scale image |
| CPD | Fax Cover document |
| CPE | Fax Cover document |
| CPF | The Complete Fax (Fax file) |
| CPH | Image file (Corel Print House) see CPO |
| CPI | ColorLab Processed Image bitmap |
| CPJ | CeQuadrant CD Project |
| CPL | Compel Presentation |
| CPM | Turbo Pascal DOS file |
| CPMZ | Used to exchange project data between Miradi and ConPro |
| CPO | Image file (Corel Print Office) |
| CPP | CA-Cricket Presents presentation |
| CPR | Corel Presents presentation |
| CPS | Coloured postscript |
| CPT | Macintosh Compressed Archive |
| CPX | Corel Presentation Exchange compressed drawing |
| CPY | Data file (Copy Books) |
| CPZ | COMPOZ Music Text |
| CRC | Cyclical Redundancy Check checksum file |
| CRD | Microsoft Windows 3.x Cardfile |
| CRF | Zortech C++ cross-reference |
| CRH | Image file (Microsoft Golf) |
| CRP | Visual dBASE custom report |
| CRS | WordPerfect 5.1 for Windows File Conversion resource |
| CRT | Oracle Terminal settings information |
| CRU | CRUSH Compressed archive |
| CS1 | Sinar CaptureShop raw file for Macintosh |
| CS16 | Sinar CaptureShop raw file for Macintosh |
| CS4 | Sinar CaptureShop raw file for Macintosh |
| CSA | Comma deliminated text |
| CSC | Corel script file |
| CSG | Statistica/w Graph file |
| CSH | C shell script files (Hamilton Labs) |
| CSM | Script file (Kodak Dc265 Camera) |
| CSO | Customer service data and outcome file |
| CSP | PC Emcee On-Screen image |
| CSS | Statistica/w Datasheet |
| CST | Macromedia Director "Cast" (resource) file |
| CSV | CompuShow Adjusted EGA/VGA Palette |
| CT | A graphic file associated with the Paint Shop Pro Graphic Editor |
| CTB | AutoCAD Color-dependent Plot Style Table |
| CTC | PC Installer Control |
| CTF | Symphony Character code translation |
| CTL |
dBase IV Control |
| CTX |
Pretty Good Privacy (PGP) Ciphertext file |
| CUE |
CDRWin (and others) Description File for a CD-Image |
| CUL |
Cursor library file (IconForge) |
| CUR |
Windows Cursor |
| CURSOR |
Sun Microsystems Cursor |
| CUT |
Dr. Halo Bitmap |
| CV |
Microsoft CodeView information screen |
| CVG |
Image |
| CVS |
Canvas drawing file |
| CWK |
Claris Works data |
| CWS |
Claris Works template |
| CXT |
Macromedia Director protected (not editable) "Cast" (resource) file |
| CXX |
C++ source code |
| CZIP |
Encrypted Zip File |
