| ccrz | Saba Centra Recording Studio Recording |
| ccv | SAP Business Objects Crystal Vision Report |
| ccw | Crossword Compiler Crossword File |
| ccz | Client-Course Manager Customized Report Distribution Data |
| cd | STK City Database Main File |
| cdb | Sybase PowerDesigner Conceptual Data Model Backup |
| cdbcmsg | CIM Database CMSG Data |
| cdcom | Circuit Diagram Compiled Components File |
| cde | CADKEY Dynamic Extension |
| cded | Canadian Digital Elevation Data |
| cdf | netCDF Data |
| cdf | ECMG Content Definition File |
| cdf | Affymetrix Chip Description File |
| cdf | ANDI/netCDF Chromatography Data |
| cdf-ms | ClickOnce Compiled Manifest |
| cdl | Common Data Form Language File |
| cdm | Sybase PowerDesigner Conceptual Data Model |
| cdmp | WCS Device Model Profile |
| cdoc | DigiDoc Crypted Document |
| cdv | CatDV Catalog |
| cdws | CorelDraw X7 Workspace |
| cdx | dBASE Compound Index |
| cdx3 | Cochlear Data Exchange File |
| ced | EEGLAB Channel Data |
| cee | CN3 Compressed Extended Ephemeris Data |
| cei | CRiSP Harvest Settings Data |
| cel | Affymetrix Probe Array Results File |
| cell | CASTEP Cell Input Data |
| celx | Celestia Script File |
| cen | CEN EN 13032 Photometric Data |
| cex | SolidWorks Enterprise PDM Exported Vault Settings |
| cez | Prosurv cEZ Job File |
| cf | CFEngine Policy Data |
| cf1 | Common Loudspeaker Format Type 1 File |
| cf2 | Common Loudspeaker Format Type 2 File |
