| flwa | Folder Lock Wallet File |
| flx | MODTRAN FLX Output File |
| flz | WinFlash Compiled Flashcard |
| fm | FileMaker Pro Data |
| fm5 | FileMaker Pro Data |
| fma | PermitMD FMA Form Definition File |
| fma | FMAudit Exported Audit Data |
| fma | PTV VISSIM Matrix Data |
| fmd | FARSITE Custom Fuel Model |
| fmdb | Ensoft Formulator Object Database |
| fmelic | FME License |
| fmi | FME Include File |
| fmod | Adobe Illustrator Flattening Module |
| fmp | FileMaker Pro Data |
| fmp12 | FileMaker Pro 12 Database |
| fmp3 | FileMaker Pro for Mac Database |
| fmpsl | FileMaker Pro 12 Snapshot Link |
| fmpur | FileMaker Pro Runtime Solution |
| fms | FARSITE Moisture Data |
| fmsh | Autodesk Inventor Mesh Data |
| fmtr | FileMaker Pro Transfer Data |
| fmu | Functional Mock-up Unit Data |
| fmw | FME Workbench |
| fn | STK Facility Networks File |
| fna | FASTA Sequence |
| fnbk | Food Network Recipe Manager Data |
| fnc | Frogans Player Network Certificate |
| fnl | EES File Names List |
| fnm | Lucene Field Name Data |
| fno | Folio Infobase Data |
| fnw | FLARENET Model Data |
| fnx | Fenix Key Data |
| fo | 602XML Form Filler Data |
| fob | Microsoft Dynamics NAV Object Container |
| foc | FOCUS Database |