| brs | WRAP Beginning Reservoir Storage Data |
| brs | Adobe RoboHelp Browse Sequence |
| bru | Brutus Restore Data |
| brushset | Procreate Brush Set Data |
| brv | Brave Viewer Thumbnail Cache |
| brw | Calyx Point Borrower |
| bs4 | Mikogo Recorded Session |
| bsb | Xilinx Base System Builder Playback File |
| bsb | NOAA Nautical Charts |
| bsc | Balanced Scorecard Designer Data |
| bsca | IBM System/3 BSCA Data |
| bsch | Bartco VMS Message Schedule Data |
| bsd | FacetWin Backup Set Description |
| bsd | Xilinx BSDL File |
| bsdl | Xilinx BSDL File |
| bsig | ClamAV Binary Signature |
| bsk | Blaise Database BSK Data |
| bsml | Bioinformatic Sequence Markup Language Document |
| bsmz | Compressed BSML Document |
| bson | Binary JSON Data |
| bsr | Bacula Bootstrap File |
| bsw | Microsoft Office Business Scorecard Manager Workspace |
| bswx | BIMReview 3D Model Data |
| bsy | VTrain Learning Card |
| bt | Binary Terrain Data |
| bt0 | Band-in-a-Box Temporary Data |
| bt2 | Batch Barcode Maker Data |
| bta | Bend-Tech v3 Assembly File |
| btax | Bend-Tech v6 Assembly File |
| btf | NationsBank Check Image |
| bth | TimeZero Bathy Recorder Data |
| btif | NationsBank Check Image |
| btk | CLwin Tekton Database |
| btmsp | MALDI BioTyper Main Spectra File |
| bto | Bryce Tree Object |