| fbv | FinalBuilder Persistent Variables File |
| fcb | FAAST Builder File |
| fce | ForeUI Custom Element |
| fcl | ForeUI Custom Library |
| 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 |
| fi | Fortran Interface File |
| fi | Gforth Image File |
| fic | WinDev HyperFileSQL Database |
| fig | MATLAB Figure |
| fil | ProWorx NXT Format Export |
| filters | Visual C++ Project Filters |
| fimpp | FiM++ Source Code |
| fky | Microsoft Visual FoxPro Macro File |
| fla | Shockwave Flash Source File |
| flash | Shockwave Flash Source File |
| flb | EasyBuilder Pro Picture Library |
| flbx | EasyBuilder Pro Picture Library |
| fll | Visual FoxPro DLL |
| flm | Flasm Disassembled SWF |