| fill | CorelDRAW Vector Fill Pattern Data |
| filp | eXtendable Wad Editor FILP Data |
| fim | Fest3D Waveguide Modes Data |
| fim | Fractal Imaginator Data |
| fin | Abaqus/CAE FIN Data |
| fingnet | Fing Saved Network Data |
| fins | Autodesk Inventor Stress Analysis FINS Data |
| fio | Aldus PhotoStyler Graphics Filter |
| fip | File Investigator Internal Database |
| firmware | WOW! Diagnostic Firmware Data |
| fis | MATLAB Fuzzy Logic Toolbox FIS File |
| fish | 3D Fish Tank Fish Data |
| fishtank | 3D Fish Tank Data |
| fitreg | netfabb Basic Data |
| fits | HippoDraw FITS Data |
| fiv | File Investigator Internal Database |
| fix | ASL Fixplot Calculated Fixations |
| fjsw | Formulator Tarsia Jigsaw Puzzle |
| fkc | FBackup Catalog File |
| fkd | FotoKiss Photo Set Data |
| fkr | FKR Program Data File |
| fl | DRM Forward Lock |
| fl3 | Adobe Photoshop Flash 3D Document |
| fl7 | PCModWin MODTRAN Output Data |
| flame | Fractal Flames Data |
| flatpakref | Linux Flatpak Package Description |
| flatpakrepo | Linux Flatpak Repository Data |
| flb | FileMaker Pro Label Data |
| fld | 3D Fassade Plus Field Data |
| fld | WinFlash Flashcard Settings |
| flexolibrary | Final Cut Pro Library Database |
| flf | Corel Paradox Delivered Form |
| flf | FLAMES License Data |
| flf | Microsoft Dynamics NAV License File |
| flg | MicroSim PCBoard Log Data |
