| fbap | FinalBuilder Action Package |
| fbl5 | FinalBuilder Project Log |
| fbl6 | FinalBuilder Project Log |
| fbp | wxFormBuilder Project |
| fbpinf | FinalBuilder Project Info |
| fbv | FinalBuilder Persistent Variables File |
| fcb | FAAST Builder File |
| fce | ForeUI Custom Element |
| fcl | ForeUI Custom Library |
| fclr | Flowgorithm Color Scheme Data |
| fcs | CC5X C Compiler Function Call Structure |
| fd | Fortran Declaration File |
| fda | FlashDevelop Argument File |
| fdb | FlashDevelop Binary File |
| fdl | FlashDevelop Layout File |
| fdm | FlashDevelop Macro |
| fdml | Filemaker Dynamic Markup Language Document |
| fdt | FlashDevelop Template |
| fdz | FlashDevelop Zip File |
| feature | SharePoint Feature Data |
| fev | FMOD Audio Events |
| fex | WebFOCUS Procedure File |
| ffe | Microsoft DirectInput Force Feedback Effect |
| fgd | Valve Hammer Forge Game Data |
| fgl | FGL Source Code |
| fhm | ASIP Meister Data |
| fhs | Adobe Flash FlashHelp Skin Data |
| fhz | Adobe Flash FlashHelp Compressed Skin Data |
| fi | Fortran Interface File |
| fi | Gforth Image File |
