| bnx | Board Neutral Exchange Data |
| bnz | The Bingo Maker Card Template |
| bobj | Blender Fluid Simulation Object |
| boe | Microsoft Outlook Express Backup Database |
| bof | Babylon License Data |
| bof | Altair FEKO POSTFEKO Binary Output Data |
| bog | PVVMUD Binary Object Geometry File |
| bok | Pearson TestGen Test Bank |
| bolts | Tekla Structures Exported Bolts Data |
| bom | PTC Creo Bill of Materials File |
| bom | Mac OS X Bill of Materials File |
| bon | Binary Object Notation Document |
| bonds | Ribbons Bonds Definition |
| bones | XtalView Xfit Ridgelines Data |
| boo | Boo Encoded Data |
| book | Budget In Brief Budget Book |
| bookexport | BookSmart Exported Books Data |
| bootskin | Stardock BootSkin Data |
| boottrees | IQ-TREE Boot Trees Data |
| bop | Vflo Model Data |
| bopx | Vflo Model Data |
| bov | VisIt BOV File |
| bow | Back Orifice 2K Workspace |
| box | CARA Loudspeaker Design |
| box | Kodicom Video Metadata |
| boxr | Boxerjam Data |
| bp | DataFlex Business Process Object |
| bp2 | Autodesk AutoCAD Batch Plot File |
| bp3 | Autodesk AutoCAD Batch Plot File |
| bpa | StorageSync Backup Archive |