| brd | KiCad Board Layout File |
| brep | Boundary Representation File |
| brf | Braille Formatted File |
| brl | BRL-CAD Document |
| bro | PrintShop Deluxe Brochure |
| brt | Photo Builder Template |
| bry2 | Bryce 2 Scene |
| bst | BibTeX Document Style |
| bt5 | ERP5 Business template |
| btab | ASCII Guitar Tab |
| btd | Business-in-a-Box Document |
| buz | Buzz Tools BuzzEdit Document |
| bwb | Visual Baler Spreadsheet |
| bwp | BuRg3r Web Page |
| bws | SmartWare Worksheet Backup |
| bxl | Accelerated Designs Binary PCB Library |
| bxu | PictureGear Studio file |
| byd | BYP Layout Document |
| bzabw | AbiWord Bzip2 Compressed Document |
| c1d | C1Report C1D Open XML Document |
| c1dx | C1Report C1D Open XML Document |
| c2w | Cybernet v2 Document |
| c3d | Chem3D Document |
| cad | Autodesk QuickCAD Document |
| cadl | CADKEY CAD Advanced Design Language File |
| cadoc | Clicker App Document |
| cae | Caditor Encrypted Document |
| cal | Broderbund PrintMaster Calendar |
| calca | Calca Document |
| calx | Calendar Printing Assistant Template |
| cap | Capella Music Score |
| capx | Capella XML Music Score |
| capxml | Capella XML Document |
| car | NeoBook Cartoon |
| car | Broderbund PrintMaster Card |