| .B1N | Unknown Developer | File vari | Binary Screen Image File | Unknown Software | Unknown Developer |
| .B2Z | Unknown Developer | File di dati | B2Z dVS Model/Object | Unknown Software | Unknown Developer |
| .B5B5 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .B7S | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BAI | B2W Software | File con plugin | BUILD2WIN Add-in | Unknown Software | Unknown Developer |
| .BAI2 | Bank Administration Institute (BAI) | File di dati | Cash Management Balance Reporting Specifications Version 2 | Unknown Software | Unknown Developer |
| .BALL | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BANNER | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BAO | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BATH | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BBZ | BitBlaze | File audio | Bitblaze Audio File | Unknown Software | Unknown Developer |
| .BCS | The Wavelength | File di settaggi | Batch Compiler Specification File | Unknown Software | Unknown Developer |
| .BDCFG | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BDIFF BUPDATE BINARY UPDATE | Unknown Developer | File di dati | Bdiff Bupdate Binary Update | Unknown Software | Unknown Developer |
| .BDMB | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BDSM | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BDU | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .BDZ | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BEACON | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BEAT | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BEATWAVE | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BER | Unknown Developer | File vari | German Bericht Report File | Unknown Software | Unknown Developer |
| .BF4 | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BFAB | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BFCE | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BFH | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BFN | Brother International Corporation | File di font | Brother Embroidery Software Font | Unknown Software | Unknown Developer |
| .BHB | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BIG | Electronic Arts | File di giochi | Electronic Arts Game Data File | Unknown Software | Unknown Developer |
| .BILL | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BIN | Unknown Developer | File con immagini disco | Binary Disk Image File | Unknown Software | Unknown Developer |
| .BJD | NDDigital | File di dati | NDDigital Print Bureau File | Unknown Software | Unknown Developer |
| .BKG | Samsung Electronics | File di dati | Samsung Document | Unknown Software | Unknown Developer |
| .BKH | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .BKL | KeyCarbon | File di dati | KeyCarbon Binary Keystroke Log | Unknown Software | Unknown Developer |
| .BKT | Zortech | File vari | Zortech Data File | Unknown Software | Unknown Developer |
| .BLACK | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BLI | Thomson Reuters Corporation | File vari | Thomson Speedtouch Firmware File | Unknown Software | Unknown Developer |
| .BLOCK | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BLOSSOMS | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BLURB | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BM_ | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BNN | Unknown Developer | File grafici | Vectorial Image File | Unknown Software | Unknown Developer |
| .BN_ | Unknown Developer | File vari | Ntgraph Ze32v215 File | Unknown Software | Unknown Developer |
| .BOA | Unknown Developer | File compressi | BOA Constrictor Compressed Archive | Unknown Software | Unknown Developer |
| .BONGO | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BOR | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BP | Data Access Worldwide | File sviluppatore | DataFlex Business Process Object | Unknown Software | Unknown Developer |
| .BPG | Open Source | File con immagini raster | Better Portable Graphics (BPG) Image | Unknown Software | Unknown Developer |
| .BPU | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BRHQUJL | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BRUSH | Xerox | File con immagini raster | Xerox Doodle Brush Bitmap Image | Unknown Software | Unknown Developer |
| .BTX | SmartWare Corporation | File backup | SmartWare Backup Text File | Unknown Software | Unknown Developer |
| .BUF | Unknown Developer | File temporanei | Buffer File | Unknown Software | Unknown Developer |
| .BUSH | Apple | File di dati | Golden Orchard Apple II CD Rom File | Unknown Software | Unknown Developer |
| .BUTTHEREIS | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BVHJBVHJ | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BWK | Unknown Developer | File vari | Unknown File Type | Unknown Software | Unknown Developer |
| .BWV | Unknown Developer | File vari | Business Wave File | Unknown Software | Unknown Developer |
| .BXX | Bitmanagement Software | File di settaggi | BS Contact Parameter File | Unknown Software | Unknown Developer |
| .BYL | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .BYZ | Unknown Developer | File vari | Uncommon File Extension | Unknown Software | Unknown Developer |
| .BZF | Unknown Developer | File di giochi | Game File | Unknown Software | Unknown Developer |
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