| Extension | File Type | Files scanned | Contributor |
| C10 | Virtual MC-10/Alice tape image | 26 | |
| C3 | 3D model | 3 | |
| C32 | Syslinux COM32 module (generic) | 3 | |
| C32 | Syslinux COM32 module (v2) | 621 | Joerg Jenderek |
| C32 | Syslinux COM32 module (v4) | 247 | Joerg Jenderek |
| C32 | Syslinux module (v5 32-bit) | 378 | Joerg Jenderek |
| C32 | Syslinux module (v5 64-bit) | 133 | Joerg Jenderek |
| C3D | Chem3D Format | 21 | |
| C3D | Chem3D model | 13 | |
| C3D | Coordinate 3D (subset of ADTech File Format) file (common) | 36 | |
| C3D | Coordinate 3D (subset of ADTech File Format) file (more generic) | 37 | |
| C3XML | Chem3D XML format | 6 | |
| C4* | Clonk game data | 20 | |
| C4D | CINEMA 4D model (generic) | 21 | |
| C4M | Clonk Material definition | 6 | |
| C64 | CCS64 Freeze saved state | 23 | |
| C64 | CCS64 snapshot (v1) | 8 | |
| C64 | PC64/DOS saved session image/dump | 4 | |
| CA1 | Crack Art bitmap (low-res) | 6 | |
| CA2 | Crack Art bitmap (med-res) | 2 | |
| CA3 | Crack Art bitmap (hi-res) | 6 | |
| CA5 | Calendar Creator 5 ClipArt Archive | 120 | |
| CAB | InstallShield compressed Archive | 14 | |
| CAB | Microsoft Cabinet Archive | 17 | |
| CAB | Microsoft Windows CE installation Cabinet Archive | 40 | Joerg Jenderek |
| CABAL | Cabal info | 29 | |
| CABAL | Cabal info (with rem) | 18 | |
| CACHE | WinUAE configuration Cache | 3 | |
| CAD | CadStd drawing | 8 | |
| CAD | Drafix Windows CAD drawing | 4 | |
| CAD | EXTRACAD drawing | 4 | |
| CAD | GenCAD layout | 11 | |
| CAD | IntroCAD drawing | 5 | |
| CAD | KiCad Drawing | 10 | |
| CAD | QuickCAD Drawing | 6 | |
| CAD | Rad Cad drawing | 5 | |
| CAF | Cal3D Animation File | 3 | |
| CAF | Cathy catalog | 659 | aNDreas Bolota |
| CAF | Core Audio File | 9 | |
| CAF | PS Vita SCECAF crash report | 2 | |
| CAG | Capella gallery data file | 7 | Joachim Grabinski |
| CAG | Create Adventure Games project | 3 | |
| CAI | SeeYou flight data | 9 | |
| CAJ | CAJ database | 13 | |
| CAJ | Chinese Academic Journal | 37 | |
| CAKEWALKSTUDIOWARE | Cakewalk Studio Ware panel | 11 | |
| CAL/CALS | CALS raster bitmap | 6 | |
| CAL | Microsoft Project 4.0 for DOS Calendar | 3 | |
| CAL | PeachCalc spreadsheet (v2.x) | 14 | |
| CAL | QV Map Calibration data | 16 | |
| CAL | SuperCalc 2/3 spreadsheet (v1.00) | 5 | |
| CAL | SuperCalc 3 spreadsheet (v2.x) | 25 | |
| CAL | SuperCalc 4 spreadsheet | 9 | |
| CAL | SuperCalc worksheet (gen) | 25 | |
| CAL | Windows Calendar | 7 | |
| CALC | EasyCalc spreadsheet (v1.0) | 2 | |
| CALC | EasyCalc spreadsheet (v2.0) | 8 | |
| CALC | SFX Advanced Calculator spreadsheet | 4 | |
| CAM | Aegis ProMotion/Videoscape 3D Camera | 11 | |
| CAM | Casio QV digital CAMera bitmap | 2 | |
| CAM | MSN Messenger ML20 video | 5 | |
| CAM | Opticks Camera | 3 | |
| CAMM | Crystal Alien Map Maker project (INI) | 12 | |
| CAMM | Crystal Alien Map Maker project (JSON) | 31 | |
| CAMM | Espresso Mind Map | 4 | |
| CAMPROJ | Camtasia Studio Project | 13 | |
| CAMPROJ | Camtasia Studio Project (UTF) | 15 | |
| CAMREC | Camtasia Studio Screen Recording | 10 | |
| CAP | Capella sheet data file | 232 | Joachim Grabinski |
| CAP | Generic network capture file (XCP style) | 4 | |
| CAP/PIC/TXM | IBM Storyboard screen Capture | 15 | |
| CAP | Java Card converted Applet | 7 | |
| CAP | Microsoft NetMon v1.x traffic capture | 5 | |
| CAP | Microsoft NetMon v2.x traffic capture | 8 | |
| CAP | Snoop capture file | 3 | |
| CAPROJ | Construct 2 Project | 16 | |
| CAPX/CAPXML | Capella CapXML music notation | 6 | |
| CAPX | Construct compressed game project | 8 | |
| CAQ | Aquarius Cassette tape image | 12 | |
| CAR | Atari Cartridge | 45 | |
| CAR | Biosym archive | 6 | |
| CAR | CAR compressed archive | 4 | |
| CAR | Carnivores /2 /Ice Age animal and object graphics and behavior file | 27 | Dinoguy1000 |
| CAR | Carrara Environment | 15 | |
| CAR | Cellsprings CA Rule | 6 | |
| CAR | NASCAR Racing 2 Car data | 59 | |
| CAR | NASCAR Racing 2002 Season Car data | 2 | |
| CAR | NASCAR Racing 3 Car data | 94 | |
| CAS | Atari Cassette tape image | 3 | |
| CAS | EACA Colour Genie virtual tape image | 4 | |
| CAS | EnCase Case data | 3 | |
| CAS | Fluent case | 6 | |
| CAS | Frostbite Container of ASsets | 2 | |
| CAS | Javelin Case study | 18 | |
| CAS | MSX cassette tape image | 19 | |
| CAS | Sord M5 tape image | 3 | |
| CASETEMPLATE | EnCase Case Template | 15 | |
| CAT | Elcomsoft ADC Advanced Disc Catalog | 12 | Christian Wolkersdorfer |
| CAT | Frostbite Catalog | 2 | |
| CAT | Microsoft Security Catalog | 6 | Joerg Jenderek |
| CAT | Microsoft Security Catalog (DER encoded) | 866 | Joerg Jenderek |
| CAT | Starcat disks catalogue | 3 | |
| CAT | WinCat disk Catalog | 2 | |
| CATALOG | Amiga Catalog translation format | 18 | |
| CATDRAWING | CATIA Drawing (generic) | 74 | |
| CATDRAWING | CATIA Drawing (v5 r10) | 8 | |
| CATDRAWING | CATIA Drawing (v5 r11) | 8 | |
| CATDRAWING | CATIA Drawing (v5 r14) | 8 | |
| CATDRAWING | CATIA Drawing (v5 r15) | 8 | |
| CATDRAWING | CATIA Drawing (v5 r16) | 8 | |
| CATDRAWING | CATIA Drawing (v5 r17) | 24 | |
| CATDRAWING | CATIA Drawing (v5 r18) | 16 | |
| CATDRAWING | CATIA Drawing (v5 r19) | 8 | |
| CATPART | CATIA Part Description (generic) | 30 | |
| CATPART | CATIA Part Description (v5 r18) | 37 | |
| CATPART | CATIA Part Description (v5 r19) | 409 | |
| CATPART | CATIA Part Description (v5 r20) | 14 | |
| CATPART | CATIA Part Description (v5 r21) | 17 | |
| CATPART | CATIA Part Description (v5 r22) | 10 | |
| CATPART | CATIA Part Description (v5 r23) | 13 | |
| CATPART | CATIA Part Description (v5 r24) | 16 | |
| CATPRODUCT | CATIA Assembly (v5 r16) | 50 | |
| CATPRODUCT | CATIA Assembly (v5 r19) | 51 | |
| CATPRODUCT | CATIA Assembly (v5 r20) | 57 | |
| CATPRODUCT | CATIA Assembly (v5 r21) | 64 | |
| CATPRODUCT | CATIA Assembly (v5 r22) | 67 | |
| CATPRODUCT | CATIA Assembly (v5 r23) | 70 | |
| CATPRODUCT | CATIA Assembly (v5 r24) | 73 | |
| CATPRODUCT | CATIA Assembly (v5 r25) | 74 | |
| CATPRODUCT | CATIA V5 Assembly (generic) | 47 | |
| CAZ | CAZIP compressed file | 3 | |
| CAZ | CAZIPXP compressed archive | 3 | |
| CBA | Chuck Biscuits/Black Artist module | 11 | |
| CBC | Clam Antivirus ByteCode signatures | 21 | |
| CBCX | Comic Book Creator document | 5 | |
| CBCX | Comic Book Creator document (Unicode) | 7 | |
| CBD | MapBrowser - MapWriter vector map data | 2 | |
| CBDS | Comic Book DS | 4 | |
| CBF | CoffeeCup Button Factory button | 14 | |
| CBF | Infinity Engine archive (v1.0) | 118 | Sam. |
| CBF | RKS Software Clandar Builder saved calendar | 7 | |
| CBH | ChessBase Light database Header | 2 | |
| CBH | ChessBase database Header | 2 | |
| CBI | CBI document | 2 | |
| CBIN | CACTVS (binary format) | 2 | |
| CBMPRJ | CBM prg Studio Project | 6 | |
| CBOARD | Final Cut Pro X Color Board preset | 6 | |
| CBP | Code::Blocks Project | 7 | |
| CBPROJ | Borland C++ Builder project | 23 | |
| CBPROJ | Borland C++ Builder project (UTF-8) | 144 | |
| CBR | The Print Shop Deluxe Certificate Borders | 2 | |
| CBS | Codebreaker save | 11 | |
| CBS | RKS Software Clandar Builder Style Sheet | 9 | |
| CBV | ChessBase Archive file | 11 | |
| CBXML | CodeBox snippet library | 8 | |
| CC3 | Calendar Creator Plus project (v4.0) | 16 | |
| CC3D | CompuCell3D project | 5 | |
| CC5 | Calendar Creator 5 project | 102 | |
| CCA | Multimedia Fusion - Click'n'Create file | 30 | |
| CCB | CocosBuilder info | 10 | |
| CCBI | CocosBuilder exported info | 7 | |
| CCC | TeslaCrypt/Cryptowall encrypted | 9 | |
| CCD | Elaborate Bytes/SlySoft CloneCD CDImage (description) | 14 | THE LoW |
| CCD | Harry Potter: Quidditch World Cup game data archive | 2 | |
| CCE | Calendar Creator Plus project (v2.0) | 85 | |
| CCF | Component Configuration File (generic) | 7 | |
| CCF | Copper Colourz! File | 4 | |
| CCF | Wii Virtual Console CCF archive | 3 | |
| CCI | Compressed Champions' Interlace bitmap | 2 | |
| CCM | Creative Commons Module music | 9 | |
| CCPROJ | Visual Studio Cloud service project | 15 | |
| CCRF | Saba Centra Recording Studio recording | 4 | Chris Clemson |
| CCS | CableNut Custom Settings | 7 | |
| CCT | Calamus Codepage Table | 10 | |
| CCT | Corncob 3D Theater-of-operation data | 4 | |
| CCT | Macromedia Director Shockwave Cast | 16 | |
| CCVF | CompuColor Virtual Floppy disk image | 8 | |
| CCW | Calendar Creator Plus Workspace (v2.0) | 5 | |
| CD | Class Diagram (UTF-8) | 7 | |
| CD | Class Diagram (Unicode) | 4 | |
| CD5 | Chasys Draw IES drawing | 42 | |
| CDA | CD Audio track shortcut | 15 | |
| CDB | CodeSuite DataBase - BitMatch | 33 | |
| CDB | CodeSuite DataBase - CodeMatch | 8 | |
| CDB | Mactive AdBase data | 2 | |
| CDB | Pocket Access database | 14 | |
| CDB | Sangduck database | 2 | |
| CDCOM | Circuit Diagram Component (compiled) | 5 | |
| CDD | Cadifra Diagram | 4 | |
| CDD | Claris Draw document | 18 | |
| CDD | ConceptDraw document | 6 | |
| CDDS | Midtown Madness 3 data | 5 | |
| CDDX | Circuit Diagram Document | 2 | |
| CDE | MicroHof Code | 4 | |
| CDF | Affymetrix Chip Definition File (Text) | 7 | |
| CDF | Channel Definition Format | 3 | |
| CDF | Computable Document Format | 12 | |
| CDF/NC | NetCDF Network Common Data Form | 20 | |
| CDF-MS | ClickOnce Compiled Manifest | 1132 | |
| CDK | Calamus Document | 9 | |
| CDL | CD Label Pro project | 2 | |
| CDL | NetCDF (network Common Data Form) | 14 | |
| CDM | NTI CD Maker image file | 4 | |
| CDM | PowerDesigner Conceptual Model | 13 | |
| CDO | Crescendo Music Notation score | 4 | |
| CDPZ | ConceptDraw Project document (Zipped) | 30 | |
| CDR | CorelDRAW drawing (generic) | 19 | |
| CDR | CorelDRAW drawing (v1.0) | 24 | |
| CDR | CorelDRAW drawing (v2.0) | 27 | |
| CDR | CorelDRAW drawing (zipped) | 18 | |
| CDR | CorelDRAW for OS/2 drawing (v2.5) | 4 | |
| CDR | CorelDraw Document | 66 | |
| CDR | Elite Plus Commander file / saved game | 5 | |
| CDR | Elite game save (PC) | 34 | |
| CDRZIP | DICOM Images zipped archive | 6 | |
| CDS | Borland Client Dataset data | 20 | |
| CDV | Javelin Country Driver | 10 | |
| CDW | CeledyDraw drawing | 54 | |
| CDW | KOMPAS Drawing | 11 | |
| CDW | KOMPAS Drawing (Unicode) | 38 | |
| CDX | CDX Internet Archive index | 4 | |
| CDX | ChemDraw model | 17 | |
| CDX | Compound index MS Visual FoxPro 7 | 180 | Nicola Marangon |
| CDX | Sybase iAnywhere index files | 207 | Knuth Konrad |
| CDXML | ChemDraw XML | 11 | |
| CDXML | PowerShell Cmdlet Definition XML | 10 | |
| CDXML | PowerShell Cmdlet Definition XML (UTF-8) | 18 | |
| CDZ | pSX compressed CD image | 10 | |
| CE1 | ComputerEyes Raw Data Format low-res bitmap | 5 | |
| CE2 | ComputerEyes Raw Data Format hi-res bitmap | 5 | |
| CEB | Apabi eBook | 10 | |
| CED | EEGLAB Channel Data | 7 | |
| CEF | Cereal Encrypted File | 2 | |
| CEG | Continuous Edge Graphic bitmap | 7 | |
| CEL | Affymetrix Probe Results (Bin) | 4 | |
| CEL | Affymetrix Probe Results (Text) | 18 | |
| CEL | Celestia script | 9 | |
| CEL | Chasm CEL bitmap | 2 | |
| CEL | KiSS CEL bitmap | 2666 | |
| CER | Internet Security Certificate | 11 | |
| CER/MSI | MSI/Accelrys Cerius II | 4 | |
| CF1 | Common Loudspeaker Format binary (v1, Type 1) | 154 | |
| CF2 | Common Loudspeaker Format binary (v1, Type 2) | 120 | |
| CF2 | Common Loudspeaker Format binary (v2, Type 2) | 14 | |
| CFC | ColdFusion Component | 16 | |
| CFC | ColdFusion Component (with rem) | 8 | |
| CFDG | Context Free design grammar | 46 | |
| CFF | BoomTracker 4.0 module | 4 | |
| CFF | Compact Font Format | 8 | |
| CFG | AGS game configuration | 7 | |
| CFG | Ableton project configuration | 10 | |
| CFG | Agat Emulator Configuration | 45 | |
| CFG | Back-It device definition (v4) | 4 | |
| CFG | Doom Configuration | 6 | |
| CFG | EISA add-on card Configuration | 24 | |
| CFG | EISA add-on card Configuration (with rem) | 24 | |
| CFG | EzCad Configuration | 6 | |
| CFG | HxC Floppy Emulator configuration | 7 | |
| CFG | KGen98 Configuration | 2 | |
| CFG | Linksys NVRAM configuration dump | 2 | |
| CFG | MS Flight Simulator aircraft configuration file | 18 | |
| CFG | Minimig Configuration | 3 | |
| CFG | ODI link driver configuration | 25 | |
| CFG | Polycom SoundPoint IP configuration | 15 | |
| CFG | Protext Configuration | 2 | |
| CFG | ShowMiiWads configuration | 4 | |
| CFG | Tomato ARM config format | 2 | |
| CFG | idMAS Configuration | 2 | |
| CFL | Compressed File Library 3 compressed data | 3 | |
| CFM | ColdFusion Template | 11 | |
| CFM | Color Font Maker pattern (v1) | 7 | |
| CFM | The Need for Speed car exterior | 39 | |
| CFML | ColdFusion Markup Language | 3 | |
| CFN | Calamus Font Data | 25 | |
| CFOSSPEED | cFosSpeed registration key | 8 | |
| CFP | CoverFactory Project | 8 | |
| CFT | CFast Animation | 13 | |
| CFT | CFast Animation (secured) | 8 | |
| CFT | Calamus Farb (Colour) Table | 16 | |
| CFT | ChiWriter low resolution screen font. | 17 | |
| CGC | Colour Genie high level tape image | 4 | |
| CGF | EGrid32 Compilable Grid Format (ready to be compiled) | 2 | Elias Montoya |
| CGF | EGrid32 Compilable Grid Format (ready to be modified) | 2 | Elias Montoya |
| CGL | Cabri 3D Language | 7 | |
| CGM | Computer Graphics Metafile (Clear Text) | 30 | |
| CGM | Computer Graphics Metafile (binary) | 401 | |
| CGP | DVDFab Change Graphic Picture | 4 | |
| CGP | NetCaptor's CaptorGroup | 5 | |
| CGP | Xilinx Core Generator System Project | 8 | |
| CGP | Xilinx Core Generator System Project (with rem) | 13 | |
| CGR | Quest3D data | 14 | |
| CGT | GOLD Parser Tables | 7 | |
| CGX | CommonGraph format | 25 | |
| CGX | CommonGraph format (UTF-8) | 3 | |
| CH | Ch file format | 2 | |
| CH | Ch file format (encrypted) | 4 | |
| CH3 | Harvard Graphics Chart (v3.x) | 233 | |
| CHAIN | Chain format | 9 | |
| CHART | MacStitch/WinStitch design | 50 | |
| CHD | MAME Compressed Hard Disk image | 2 | |
| CHECKPOINTS | Multibit Blockchain Checkpoints data | 3 | |
| CHESSTITANSSAVE-MS | Microsoft Chess Titans Saved game | 5 | |
| CHI | ChiWriter document (v3.x or older) | 4 | |
| CHI | ChiWriter document (v4.x) | 8 | |
| CHI | Chip Tracker module | 2 | |
| CHI | Windows HELP Index | 213 | |
| CHK | PolySpace check results | 7923 | aNDreas Bolota |
| CHL | Black and White 2 game data script | 6 | |
| CHL | Chile compressed file | 2 | |
| CHM | Windows HELP File | 226 | Davide "Airex" Airaghi |
| CHN | ApBasic Chain file/module | 3 | |
| CHN | Turbo Pascal 2.0 Chain module | 6 | |
| CHN | Turbo Pascal 3.0 Chain module | 12 | |
| CHO | Playmation Chor data | 25 | |
| CHORDS | SuperJAM! Chords | 43 | |
| CHP | CHP! - CH compressor for Picture! compressed bitmap | 2 | |
| CHP | VP-Expert Help System | 3 | |
| CHP | Ventura Publisher Chapter | 46 | |
| CHP | Ventura Publisher Chapter | 52 | |
| CHR | BGI (Borland Graphics Interface) font | 18 | |
| CHR | Graphic Master charset | 8 | |
| CHR | Infinity Engine exported player Character (generic) | 6 | |
| CHR | Infinity Engine exported player Character (v1.2) | 2 | |
| CHR | Infinity Engine exported player Character (v2.0) | 2 | |
| CHR | Infinity Engine exported player Character (v2.2) | 2 | |
| CHR | Infinity Engine exported player Character (v9.0) | 2 | |
| CHR | PaintShow Font | 12 | |
| CHR | SRI PeakSimple chromatogram | 9 | |
| CHR0 | Wii Model Animation | 2 | |
| CHT | Harvard Graphics Chart (v2.x) | 125 | |
| CHT | Harvard Graphics Chart (vA.01) | 3 | |
| CHT | NES emulator Cheats (var1) | 140 | |
| CHT | NES emulator Cheats (var2) | 22 | |
| CHT/SCT | SPSS template | 6 | |
| CHU | Infinity Engine user interface description (V1) | 2 | |
| CHX | CHX font format | 2 | |
| CHZ | ChArc compressed archive | 5 | |
| CI | CyberTracker Instrument | 69 | |
| CIF | BoomTracker 4.0 instrument | 82 | |
| CIF | CleWin CIF layout | 10 | |
| CIF | Crystallographic Information File | 4 | |
| CIL | Clip Gallery Download Package | 3 | |
| CIN | Calculux Indoor project | 2 | |
| CIN | Cinemaware music | 12 | |
| CIN | Delphine CIN video | 2 | |
| CIN | Id Software Quake II Cinematic video | 6 | |
| CIN | Kodak Cineon bitmap | 26 | |
| CINE | Phantom Cine video | 9 | |
| CINEMA4D | Cinema 4D project | 7 | |
| CIP | Cisco IP Phone Image bitmap | 3 | |
| CIRC | Logisim Circuit | 31 | |
| CIRCUIT | KTechlab circuit design | 7 | |
| CISO/CSO/WBI | CISO Compressed ISO CD image | 7 | |
| CIV5MAP | Civilization 5 Map | 42 | |
| CIV5PROJ | Civilization 5 Project | 14 | |
| CIV5SAVE | Civilization V saved game | 16 | |
| CIV5SLN | Visual Studio Civilization 5 Solution | 15 | |
| CJR | Panasonic JR Cassette image | 66 | |
| CKB | Cricket Audio Bank | 10 | |
| CKBX | Cricket Audio XML Bank Description | 8 | |
| CKD | Cadkey Design file | 6 | |
| CKD | KeyCreator Design file | 5 | |
| CKF | Casio Keyboard File | 23 | |
| CKIT | Compression KIT compressed C64 disk | 2 | |
| CKT | CircuitMaker schematic | 92 | Renan |
| CL2 | Hy-Tek Meet Results | 11 | |
| CL2ARC | Comic Life 2 Archive | 8 | |
| CL4 | Easy CD Creator 4 Layout | 14 | |
| CL5 | Easy CD Creator 5 Layout | 14 | |
| CLA | CLASS336 Markup Language | 6 | |
| CLASS | Java bytecode | 181 | |
| CLB | COM+ catalog file | 7 | |
| CLB | CONTEC Logger Binary data | 4 | |
| CLB | CardSoft PCMCIA Card Library | 32 | |
| CLBX | MP3 Automagic CD Cover Creator label | 6 | |
| CLD | World Construction Set Cloud map | 2 | |
| CLF | ListPro data | 14 | |
| CLF | Source Insight Custom Language File | 10 | |
| CLG | Collage Maker document | 4 | |
| CLIPS | Programmer's Notepad text Clips | 18 | |
| CLIPS | Programmer's Notepad text Clips (UTF-8) | 4 | |
| CLK | ClickFORMS data | 8 | |
| CLK | Corel R.A.V.E. Animation | 9 | |
| CLK | WatchGuard cloaked file | 2 | |
| CLKX | Crick Software Clicker File | 18 | Andrew Burt |
| CLMOV | Clan Lord movie - Visiostone | 8 | |
| CLO/CLOE | Cloe picture bitmap (big endian) | 2 | |
| CLO/CLOE | Cloe picture bitmap (little endian) | 2 | |
| CLO | SPSS Chart Look | 8 | |
| CLP | DeskMate clipart | 28 | |
| CLP | Quattro Pro Clip art | 54 | |
| CLPI | Blu-ray Clip AV stream | 4 | |
| CLR | 3ds UI colors | 17 | |
| CLR | Macromedia Flash Color Table File | 8 | .Cryorb |
| CLR0 | Wii Color Swapping Animation | 2 | |
| CLS | Visual Basic class definition | 24 | |
| CLY | The Print Shop Deluxe Card Layout | 2 | |
| CM | Brief Compiled Macro (generic) | 6 | |
| CM | Brief Compiled Macro (v1.x) | 20 | |
| CM | Brief Compiled Macro (v3.x) | 41 | |
| CM | The Chessmaster 2000 saved game | 109 | |
| CMA | OCaml bytecode (library) | 17 | |
| CMAP/PAL/IFF | IFF Color Map | 26 | |
| CMATE | ControllerMate programming | 15 | |
| CMB | Reason Combinator Instrument Patch | 8 | |
| CMBL | Vernier Logger Pro data | 83 | |
| CMC | Comic Collector Collection data | 4 | |
| CMD5/CMDF/CMMF | CrystalMaker Data format (generic) | 1860 | |
| CMD5 | CrystalMaker Data format (v5-6) | 1802 | |
| CMDF | CrystalMaker Data format (v2-4) | 22 | |
| CMF | Cal3D Mesh File | 2 | |
| CMF | Creative Music Format | 13 | |
| CMF | Sangduck Map | 2 | |
| CMG | Chessmaster saved game (10th ed.) | 2 | |
| CMG | Chessmaster saved game (generic) | 2 | |
| CMG | Cramfs ROM filesystem package | 3 | |
| CMI | OCaml bytecode (compiled interface) | 2 | |
| CML | Chemical Markup Language | 34 | |
| CML | Chemical Markup Language XML document | 5 | |
| CML | ChordML music document | 3 | |
| CMML | Continuous Media Markup Language | 12 | |
| CMO | OCaml bytecode (object) | 2 | |
| CMOD | Celestia 3D model (ASCII) | 2 | |
| CMOD | Celestia 3D model (binary) | 3 | |
| CMP | AUKTOOLS 2000 compressed archive | 3 | David J Walker |
| CMP | DCS Campaign script | 11 | |
| CMP | KiCad footprint information | 12 | |
| CMP | Moonbase Commander game data archive | 2 | |
| CMP | THEOS compressed archive | 11 | |
| CMPROJ | Channel Master Project | 36 | |
| CMR | SeeYou Raster Map | 7 | |
| CMS | Creative Music System music | 132 | |
| CMU | CMU Window Manager bitmap | 19 | |
| CMU | CMU format - Andrew Toolkit | 3 | |
| CMV | CMV compressed data | 3 | |
| CMV | Corel Movie animation | 3 | |
| CMX | Corel Metafile Exchange Image (Legacy) | 60 | Alex Paven |
| CMX | Corel Metafile Exchange Image (v16) | 5 | Joerg Jenderek |
| CMX | OCaml bytecode (native object) | 2 | |
| CMXA | OCaml bytecode (native library) | 2 | |
| CMZ | Compressed archive | 31 | |
| CN | Copy Numbers format | 15 | |
| CNC3REPLAY | Command and Conquer 3 replay | 4 | |
| CNDF | Compressed Channel Data File | 4 | |
| CNF | Lotus 123 configuration (V1) | 3 | Joerg Jenderek |
| CNF | Lotus 123 configuration (V2.2) | 2 | Joerg Jenderek |
| CNF | Lotus 123 configuration (V2.3) | 2 | Joerg Jenderek |
| CNF | Lotus 123 configuration (V2.4J) | 1 | Joerg Jenderek |
| CNF | Lotus 123 configuration (V3) | 2 | Joerg Jenderek |
| CNF | Lotus 123 configuration (V4) | 1 | Joerg Jenderek |
| CNF | Lotus 123/Symphony worksheet/format/configuration (V1-V2) | 13 | Joerg Jenderek |
| CNF | Lotus Symphony configuration | 2 | Joerg Jenderek |
| CNF | PlayStation 2 system configuration | 3 | |
| CNF | Varsity Scripsit Configuration | 2 | |
| CNM | Arxel video | 2 | |
| CNT | Help File Contents | 5 | |
| CNT/DTA | Hidden and Dangerous game data archive | 4 | |
| CNT | Painter 3D Contour | 2 | |
| CNV | DB2 Conversion File | 52 | Roberto 'rbnet' Bolli |
| CO | Cult3D object | 9 | |
| COASTS | AmiAtlas Coasts data | 2 | |
| COB | Caligari TrueSpace Object | 25 | |
| COD | Atlantis Word Processor encrypted document | 3 | |
| COD | Blackberry Binary Executable | 20 | |
| COD | Forte Agent Charmap | 38 | fenixproductions |
| COD | Lightning Strike bitmap | 4 | |
| COD/LOD/OVR | Microsoft p-code | 7 | |
| COD | Oberon V4 AsciiCoder archive | 8 | Romiras |
| COD | PlayStation RSD Coordinates (gen) | 6 | |
| COD | PlayStation RSD Coordinates (v3.0) | 2 | |
| COK | Cookeo recipe | 5 | |
| COL | Grand Theft Auto 3 collision data | 5 | |
| COL | HTML Help Collection | 6 | |
| COL | PPrint Color map | 2 | |
| COLOR/COLOR1 | Montage Color data | 8 | |
| COM | 16bit COM LHarc SFX archive executable | 3 | |
| COM | 16bit COM executable BAT2EXEC v1.3 | 65 | |
| COM | 16bit COM executable BAT2EXEC v1.5 | 3 | |
| COM | 16bit COM executable BatLite (v1.x) | 4 | |
| COM | 16bit DOS command MoonRock+Arrowsoft Asm. | 16 | |
| COM | ASIC compiled DOS COM | 8 | |
| COM | Borland Turbo Pascal 2.0x DOS Command | 13 | |
| COM | Borland Turbo Pascal 3.0x DOS Command | 16 | |
| COM | COM-Pack library | 4 | |
| COM | CP/M 3 COM binary (no RSX) | 2 | |
| COM | EICAR antivirus test file | 5 | |
| COM | ICE compressed/scrambled DOS Command | 3 | |
| COM | LGLZ compressed DOS command | 16 | |
| COM | PMarc CP/M SFX archive | 2 | Joerg Jenderek |
| COM | PopCom CP/M compressed executable | 3 | Joerg Jenderek |
| COM | SCRNCH compressed 16bit DOS executable | 6 | |
| COM | Shrink packed DOS Command | 14 | |
| COM | Six-2-Four (624) packed DOS Command | 13 | |
| COM | Sydex GENCOM CP/M translated 16bit DOS executable | 5 | |
| COM | TheDraw COM file screen save | 8 | |
| COM | ZBASIC MS-DOS COM executable (v4.0x) | 6 | |
| COMFYCAKESSAVE-MS | Comfy Cakes saved game | 6 | |
| COMICDOC | Comic Life Document | 81 | |
| COMICLIFE | Comic Life Document | 7 | |
| COMPANYLOGO | CompanyLogoDesigner project file | 429 | Thomas Holz |
| COMPILED | Flare3D Shader Language Compiled | 38 | |
| COMPOSITEFONT | Windows Composite Font | 13 | Stef |
| COMX | COMX-35 program | 448 | |
| CONF | fswebcam configuration | 4 | |
| CONF | psitree router configuration | 11 | |
| CONFIG | AmiDock Configuration | 2 | |
| CONTACT | Windows Contact | 20 | |
| CONTEST | BAMZOOKi Contest | 18 | |
| CONTROL | HEC-HMS Control specifications data | 3 | |
| COOKIE/TXT | libwww-perl cookie_jar | 5 | |
| COP/ET/ETC/T | E-Tracker chiptune | 10 | |
| COR | 42's Core War compiled program | 78 | |
| COR | WinArcadia Recording/macro | 7 | |
| CORE | Core Design module | 7 | |
| COS | WinArcadia Saved State | 10 | |
| COUNTRY | AmiAtlas Country data | 3 | |
| COW | Copy On Write disk image | 3 | |
| CP$ | Compressed data | 47 | |
| CP2 | PSFTools CodePage map | 48 | |
| CP2 | SNATCH-IT disk image | 3 | |
| CPC/CPI | Cartesian Perceptual Compression Image bitmap | 28 | |
| CPCK | Professor Layton game data package | 2 | |
| CPE | Windows FAX cover | 4 | |
| CPF | Canon EOS Custom Picture Profile | 13 | |
| CPF | Consolidated Laser Ranging Prediction Format | 5 | |
| CPG | Cool Page Project | 24 | |
| CPH | Corel PrintHouse image | 10 | |
| CPI | AVCHD Clip Information | 6 | |
| CPI | DR-DOS International Code Page Info | 2 | |
| CPI | MS-DOS International Code Page Info | 19 | |
| CPI | Sietronics CPI XRD format | 9 | |
| CPIO | CPIO archive (binary) | 4 | |
| CPIO | CPIO archive (byte swapped binary) | 6 | |
| CPIO | CPIO archive (portable) | 5 | |
| CPJ | WinOnCD Project | 8 | |
| CPK/CAK/FILM | Sega CPK video | 15 | |
| CPL | Corel Color Palette | 100 | |
| CPL | Win 9x/ME Control Panel applet | 105 | |
| CPR | CPC Plus Cartridge image | 26 | |
| CPR | Cubase Project | 26 | |
| CPS | Corel PhotoHouse image | 12 | |
| CPS | The Powder Toy Compressed Powder Save | 12 | |
| CPT | Corel Photo Paint bitmap (generic) | 161 | Joerg Jenderek |
| CPT | DTS Compact audio | 3 | |
| CPT | Mac Compactor (Pro) Archive | 8 | |
| CPV | Polytron VCS logfile | 2 | |
| CPX | Atari Control Panel applet | 3 | |
| CPX/FLT | ImgStar bitmap | 3 | |
| CPX | Windows codepage translator | 7 | |
| CR2 | Poser character rigging | 28 | |
| CR2 | RAW File from Canon digital camera | 9 | |
| CRAFT | Kerbal Space Program (KSP) spacecraft | 38 | |
| CRAM | Compressed Alignment format | 2 | |
| CRASH | Mac OS X crash log | 38 | |
| CRC | Total Commander CRC file | 2 | |
| CRD | PPC Organiser Card | 8 | |
| CRD | Windows Cardfile database (new) | 2 | |
| CRD | Windows Cardfile database (old) | 7 | |
| CRE | Infinity Engine Creature (generic) | 6170 | Sam. |
| CRE | Infinity Engine creature (v1.0) | 5 | |
| CRE | Infinity Engine creature (v1.2) | 5 | |
| CRE | Infinity Engine creature (v2.2) | 2 | |
| CRE | Infinity Engine creature (v9.0) | 2 | |
| CRF | Cal3D material File | 2 | |
| CRF/CCRF/PRN | Calcomp raster bitmap | 90 | |
| CRG | Calamus Raster Graphic bitmap | 4 | |
| CRI | Calamus Raster Information | 48 | |
| CRL | Calamus Ruler List | 2 | |
| CRP | Colossal Raw asset Package | 4 | |
| CRPLUGIN | ComicRack plugin | 5 | |
| CRS | StepMania Course | 4 | |
| CRT | C64 Cartridge image | 22 | TLG |
| CRT | Security Certificate | 6 | |
| CRT | X.509v3 security certificate | 17 | |
| CRU | Crush compressed archive | 7 | |
| CRV | Corel PhotoPaint Tone Curve | 10 | |
| CRV | vCarve Pro design | 7 | |
| CRV3D | Vectric Aspire 3D drawing | 20 | |
| CRW | Canon RAW format | 156 | Roberto 'rbnet' Bolli |
| CRX | Google Chrome Extension | 10 | |
| CRYPT | Cryptx encrypted data | 2 | |
| CRYPT | WhatsApp stored messages | 2 | |
| CRYPT7 | WhatsApp encrypted database | 10 | |
| CRYPTOMITE | CryptoMite encrypted | 21 | |
| CRYPTOMITE | CryptoMite encrypted archive | 5 | |
| CRYSISJMSF | Crysis saved game | 14 | |
| CRYSISPSF | Crysis Warhead saved game | 5 | |
| CS | ColorSchemer Studio Color Scheme | 19 | |
| CS0 | Callus savestate | 5 | |
| CSA | CSArc compressed archive | 2 | |
| CSAPLAN | SPSS Analysis Plan | 7 | |
| CSC | CSC compressed archive | 3 | |
| CSC | Canon Design Essentials printer info | 24 | |
| CSCFG | Azure Service Configuration Schema | 6 | |
| CSCFG | Azure Service Configuration Schema (UTF-8) | 5 | |
| CSCHEME | Caffeine Scheme | 44 | |
| CSD | Cabbage script | 83 | |
| CSD | Cabbage script (with rem) | 158 | |
| CSD | CorelDRAW Character Set | 2 | |
| CSD | Csound unified file format | 48 | |
| CSD | Singer embroidery design | 4 | |
| CSDEF | Azure Service Definition schema | 8 | |
| CSDL | ADO.NET Conceptual Schema Definition Language | 8 | |
| CSF | Cal3D Skeleton File | 4 | |
| CSF | CodeSuite Filter | 5 | |
| CSF | Content Sealed Format | 8 | |
| CSF | GeoMedia Coordinate System File | 5 | |
| CSF | Quartus Compiler Setting File | 15 | |
| CSG | The Virtual ColecoVision Save Game | 3 | |
| CSH | Adobe Photoshop Custom Shape | 13 | |
| CSL | Calamus textStyle List | 2 | |
| CSL | Citation Style Language | 6 | |
| CSM | CASL compiled PalmPilot program | 15 | |
| CSM | Motion Capture File Format | 125 | Alex Paven |
| CSO | DirectX Compiled Shader Object | 28 | |
| CSP | Aladdin 4D Spline | 13 | |
| CSP | AudioZip encoded audio | 7 | |
| CSP | CASLwin executable | 15 | |
| CSP | Creative Signal Processor microcode | 12 | |
| CSPLAN | SPSS Sampling Plan | 5 | |
| CSPROJ | Visual Studio C# Project | 22 | Ryan Jones |
| CSS | Cartoon Studio Script | 6 | |
| CSV | Weather Analytics data | 3 | |
| CSW | Compressed Square Wave (v1.1) | 11 | |
| CSW | Compressed Square Wave (v2.0) | 6 | |
| CT | Cheat Engine Cheat Table | 6 | |
| CT | Cheat Engine Cheat Table (XML) | 17 | |
| CT | CyberTracker 64 chiptune | 32 | |
| CT | Scitex Continuous Tone bitmap | 2 | |
| CTB | AutoCAD Color-Based Plot Style | 119 | Peter Glasl |
| CTB | CherryTree note (SQLite) | 6 | |
| CTD | CherryTree note (XML) | 4 | |
| CTD | Sony ClickToDvd Project | 4 | |
| CTE | Classical Text Editor document (v7) | 6 | |
| CTE | Classical Text Editor document (v8) | 6 | |
| CTE | Classical Text Editor document (v9) | 7 | |
| CTF | WhereIsIt? catalog file | 10 | fenixproductions |
| CTG | Canon Photo Info file | 12 | |
| CTI | Bitz and Pixels XML (ASCII)Report Template Info for collectorz.com products | 18 | Robert Williams |
| CTL | Phoenix Visual Designer third party control | 11 | |
| CTL | Visual Basic user-defined control file | 8 | |
| CTM | OpenCTM 3D mesh | 10 | |
| CTP | CrazyTalk Project | 7 | Stef |
| CTR | ChemDraw Template | 24 | |
| CTS | TreeSheets project | 14 | |
| CTT | MSN Messenger Saved Contact List | 5 | |
| CTW | Context tree weighing (CTW) compressed file | 9 | |
| CTX | Gasteiger group CTX | 7 | |
| CTX | Softdisk Text Compressor compressed data | 2 | |
| CTX | Sundial Clearlook document | 22 | |
| CTXT | BlueJ Class Context | 12 | |
| CUB | Isis Cube data | 9 | |
| CUB | SeeYou Airspace | 3 | |
| CUBE | Gaussian Cube data | 4 | |
| CUE | ISO CDImage cue/description - Data | 6 | |
| CUE | ISO CDImage cue/description - Data (with remark) | 8 | |
| CUEPROFILE | Corsair Utility Engine Profile (v2) | 278 | |
| CUI | AutoCAD Custom User Interface | 10 | |
| CUR | Windows Cursor shape | 121 | |
| CURSORFX | CursorFX theme | 14 | |
| CURXPTHEME | CursorXP theme | 13 | |
| CUS | Delitracker Customplay module | 365 | |
| CUS | Flexidump Custom printer driver | 55 | |
| CVA | Compaq Diagnostics | 33 | |
| CVC | Cybiko Video Container video | 10 | |
| CVD | Calamus Vector Document | 18 | |
| CVD/CLD/CUD/INFO | Clam AntiVirus Database | 10 | |
| CVF | Jet-VoiceMail audio data | 3 | |
| CVG | Calamus Vector Graphic | 12 | |
| CVP | WinFax Cover Page | 7 | |
| CVR | QuickLink Fax Cover | 2 | |
| CVS | Satori Paint Canvas | 40 | |
| CVT | GEOS ConVerT container format | 4 | |
| CVX | Covox ADPCM encoded audio | 8 | |
| CVZ | VZ200 Cassette image | 25 | |
| CWD | Cardwar Cards deck | 8 | |
| CWG | Castle of the Winds saved Game | 4 | |
| CWK | Claris Works document | 14 | |
| CWK | Claris Works text (MacBinary) | 7 | |
| CWK | Claris Works word processor (MacBinary) | 7 | |
| CWP | Cakewalk SONAR project | 20 | |
| CWR | WrapCandy template | 11 | |
| CWS | Combustion v2 WorkSpace project | 6 | Alex Paven |
| CWT | CWTool disk image (binary) | 2 | |
| CWT | CWTool disk image (text) | 2 | |
| CWW | Crossword Weaver puzzle | 10 | |
| CWY | SongTrix Style | 27 | |
| CXF | CTXf compressed archive | 3 | |
| CXF | CXF Vector Map Format (v1.x) | 2 | |
| CXF | CXF Vector Map Format (v2.x) | 2 | |
| CXF | CXF Vector Map Format (v3.x) | 2 | |
| CXF | Cuttlefish eXtended Format | 4 | |
| CXF | Picasa collage | 3 | |
| CXF | QCad II Font | 8 | |
| CXI | Coherent X-ray Imaging format | 5 | |
| CXT | Adobe Director Protected Cast | 8 | |
| CYG | CryoGen ECC data | 4 | |
| CYP | Crocodile Physics Simulation | 28 | |
| CZD | Crash Zone Drawing | 4 | |
| CZIP | ZipGenius encrypted compressed archive | 6 | |
