| blob | Valve Steam Client Registry Data |
| blockplt | Lego Mindstorms NXT Block Palette Data |
| blr | Biacore BIAlite Project Data |
| blrb | Apple Extensions Manager Info Data |
| blt | AOL Instant Messenger Buddy List File |
| bluebutton | VA Blue Button Data |
| bluestacks | BlueStacks App Player Data |
| blwd | Claris Home Page Data |
| blx | Magellan Mapsend Map Data |
| bm2 | Boardmaker Board |
| bm3 | Sony Ericsson PC Suite Backup |
| bmap | Block Map File |
| bmb | Onyx BAMBOO Modeler Data |
| bmd5 | BookmarkingDaemon Data |
| bmdx | eXtendable Wad Editor BMDX Data |
| bmi | Blaise Metafile |
| bmk | WindLDR Bookmarks File |
| bmk | Windows Help Bookmark |
| bml | Blaise Mode Library |
| bmml | Balsamiq Mockups Markup Language File |
| bmp | BPM Studio Skin Bitmap |
| bmpenx | Egis Encrypted BMP Data |
| bmpskin | Blaze Media Pro Skin |
| bmpx | Egis Encrypted BMP Data |
| bmr | Sybase PowerDesigner Multimodel Report Backup |
| bmrb | BMRB Chemical Shift List |
| bmrl | Balsamiq Mockups Data |
| bms | BeMusic Script |
| bmsh | Edge Mesh Data |
| bmsk | STK Body Mask File |
