| frg | DBase IV Uncompiled Report |
| frm | Visual Basic Form |
| frt | Forth Source Code |
| frt | Visual FoxPro Report Memo |
| frx | Visual FoxPro Report |
| fs | F# Implementation |
| fs | Forth Source Code |
| fsb | Form Z Compiled Script |
| fscr | ChromeEd Forester Data Script |
| fsi | F# Signature File |
| fsl | Form Z Script |
| fsq | CryENGINE Facial Editor Sequence |
| fsscript | F# Script |
| fsx | F# Script |
| ftd | Falcon Template Document |
| fth | Forth Source Code |
| ftl | FreeMarker Template |
| ftlh | FreeMarker HTML Template |
| ftlx | FreeMarker XML Template |
| ftn | Fortran Source Code |
| ftr | Falcon Translation |
| ftt | Falcon Translation Template |
| ftx | WinDev HyperFileSQL Full-text Index |
| fw4 | Framework IV File |
| fwx | FoxWeb Script |
| fx | Microsoft DirectX D3D Effect |
| fxa | FaceFX Actor File |
| fxh | XNA Game Studio HLSL Header File |
| fxl | FaceFX Language File |
| fxml | JavaFX Interface Description |
