| fci | Erosion 3D Inflow Table |
| fci | Fiery Clone Tool Image |
| fciv | Microsoft File Checksum Integrity Verifier Data |
| fcm | Brother ScanNCut Data |
| fcod | Adobe PageMaker Filter Data |
| fcp | FLAMES Checkpoint Restart Data |
| fcpcache | Final Cut Pro Cache Data |
| fcpevent | Final Cut Pro Event Data |
| fcpxdest | Final Cut Pro Share Destination Data |
| fcs | Canon ZoomBrowser EX Data |
| fcs | Flow Cytometry Standard Data |
| fcst | Delft-FEWS Forecast Data |
| fct | FolderClone Task List |
| fcxr | FileCapsule Deluxe Data |
| fcxu | FileCapsule Deluxe Data |
| fcz | Poser Compressed Face Data |
| fd | STK Facility Database Main File |
| fd1 | Windows Live Photo Gallery Thumbnail Database |
| fdat | Fiasco Database Data File |
| fdata | NONMEM Data |
| fdb | Firebird SQL Database |
| fdb | FormTool Pro Form Data |
| fdc | Autodesk AutoCAD Fields Description |
| fdd | FlexiDATA Database |
| fde | AFP Form Definition |
| fde | FLAMES Dataset Export Data |
| fdf | Format Description File |
| fdf | Origin Fitting Function Definition File |
| fdff | Fast Duplicate File Finder Data |
| fdk | Fluentizer Dictionary Data |
| fdlang2 | FeedDemon Language Data |
| fdlang4 | FeedDemon Language Data |
| fdm | SIPINA FDM Data |
| fdn | MODFLOW Drawdown Data |
| fdo | ModelSim Script |