| fcst | Delft-FEWS Forecast Data |
| fct | Campaign Cartographer Data |
| fct | FolderClone Task List |
| fcw | Campaign Cartographer v2 Data |
| fcxr | FileCapsule Deluxe Data |
| fcxu | FileCapsule Deluxe Data |
| fcz | Poser Compressed Face Data |
| fd | DataFlex Data File |
| fd | LaTeX Font Definition 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 |
| fdb | Microsoft Dynamics NAV Database |
| fdb | Navision Financials Database |
| fdb | Portfolio Catalog Data |
| fdc | Autodesk AutoCAD Fields Description |
| fdc | McAfee Sniffer Capture Data |
| 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 |
| fdi | FormDocs Index |
| fdk | Fluentizer Dictionary Data |
| fdlang2 | FeedDemon Language Data |
| fdlang4 | FeedDemon Language Data |
