| fb! | FlashGet Unfinished File |
| fb1 | FAWAVE Data File |
| fba | FinalBurn Alpha Image |
| fbat | FAR HTML Batch Compile Data |
| fbc | Family Tree Maker Compressed Backup Data |
| fbexplore | FileBoss Explorer Data |
| fbk | Microsoft Dynamics NAV Database Backup |
| fbk | Family Tree Maker Backup Data |
| fbl | iGO Map file |
| fbmod | Frosty Tool Suite Data |
| fbn | Sony-Ericsson Phone Flash Filesystem |
| fbr | BrainVoyager QX Fiber Coordinates Data |
| fbv | GrafNav Exported Binary Values Data |
| fbwinsx | FileBoss Internal Data |
| fc1 | FCEUX Saved State |
| fc2 | Poser Face Data |
| fc2 | FCEUX Saved State |
| fc3 | FCEUX Saved State |
| fca | Omnis Web Client Form Cache |
| fcat | Fact200 Categories Data |
| fcc | SiteMinder Forms Credential Collector Data |
| fcdot | ABBYY FlexiCapture Engine Document Definition |
| fcg | GAUSS Engine Compiled Gauss Data |
| fch | Gaussian Formatted Checkpoint File |
| fchk | Gaussian Formatted Checkpoint File |
| fci | Erosion 3D Inflow Table |
| fci | Fiery Clone Tool Image |
| fciv | Microsoft File Checksum Integrity Verifier Data |
| fcm | Brother ScanNCut Data |
| fcpcache | Final Cut Pro Cache Data |
| fcpevent | Final Cut Pro Event Data |
| fcs | Canon ZoomBrowser EX Data |
| fcs | Flow Cytometry Standard Data |
| fcst | Delft-FEWS Forecast Data |
| fct | FolderClone Task List |