| 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 |
| flb | FileMaker Pro Label Data |
| fld | 3D Fassade Plus Field Data |
| fld | WinFlash Flashcard Settings |
| flexolibrary | Final Cut Pro Library Database |
| flf | Microsoft Dynamics NAV License File |
| flib | Foxit Reader Library |
| flipchart | ActivInspire Flipchart |
| flk | Folder Lock Data |
| flka | Folder Lock FAT32 Portable Locker File |
| flkb | Folder Lock NTFS Portable Locker File |
| flkey | Fruity Loops Studio License Key |
| fln | XMap Flight Plan Data |
| flo | LightCycler v3 Experiment Data |
| flo | WRAP Inflow IN Records Data |
| flow | Microsoft Expression SketchFlow Data |
| flp | ActivInspire Flipchart |
| flp | Fractal Explorer Landscape Project |
| flr | WinFlash Results File |
| fls | Creator Fault List File |
| fls | WinFlash Flashcard Source |
| flt | WinFlash Compiled Test |
| fltr | XTND Filter |
| flu | WinFlash Flashcard Source (new) |
| flw | Fluke LinkWare Database |
| flwa | Folder Lock Wallet File |
| flx | MODTRAN FLX Output File |
| flz | WinFlash Compiled Flashcard |
| fm | FileMaker Pro Data |