| 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 |
| flam3 | Fractal Flames |
| flame | Fractal Flames Data |
| flatpakref | Linux Flatpak Package Description |
| flatpakrepo | Linux Flatpak Repository Data |
| flb | FileMaker Pro Label Data |
| flc | FIGlet Control Data |
| fld | 3D Fassade Plus Field Data |
| fld | Hijaak Thumbnail Folder |
| fld | WinFlash Flashcard Settings |
| flex | Flexi Data Smoothing Data |
| flexolibrary | Final Cut Pro Library Database |
| flf | Corel Paradox Delivered Form |
| flf | FIGlet Figletized Text Font |
| flf | FLAMES License Data |
| flf | Microsoft Dynamics NAV License File |
| flf | Navision Financials License Data |
| flg | MicroSim PCBoard Log Data |
| flg | Puppy Linux Partition Flag |
| fli | Autodesk Animator Mask Data |
| flib | Foxit Reader Library |
| flic | Autodesk Animator Mask Data |
