| 1 | B | IBM | IBM Lotus Applause Batch List Format |
| 2 | B2F | RISCOS Ltd. | RISC OS Windows Metafile |
| 3 | B3D | MAXON Computer GmbH | BodyPaint 3D Format |
| 4 | B4P | N/A | Native Instruments B4 II preset |
| 5 | B4S | Nullsoft | Winamp Playlist Format |
|
| 6 | B5I | VSO Software | BlindWrite Image Format |
| 7 | B5L | Smart Projects | BlindWrite Image |
| 8 | B5T | VSO Software | BlindWrite Image Format |
| 9 | B60 | RISCOS Ltd. | RISC OS PNG Bitmap Image |
| 10 | B64 | N/A | Base64 MIME-Encoded Format |
| 11 | B6I | VSO Software | BlindWrite 6 Disc Image |
| 12 | B6T | VSO Software | BlindWrite 6 Track Information Format |
| 13 | BA1 | Microsoft Corporation | Microsoft Windows Media Center Report Log |
| 14 | BA2 | Bethesda Softworks | Bethesda Softworks Archive |
| 15 | BAC | Avantrix | Backup Format |
| 16 | BACKUPDB | Apple | Apple Time Machine Backup Folder Format |
| 17 | BAF | Electronic Arts, Inc. | Battlefield 2 Animation |
| 18 | BAG | Blueprint Software Works, Inc. | PMMail Mail Index |
| 19 | BAL | N/A | Borland Programming Language Source Code |
| 20 | BAND | Apple | GarageBand Project Format |
| 21 | BAR | Microsoft | Age Of Empires 3 Data Format |
| 22 | BAROC | N/A | IBM Tivoli console adapter description |
| 23 | BAS | N/A | BASIC Source Code Format |
| 24 | BASECONFIG | Apple, Inc. | AirPort Utility Setting |
| 25 | BASH | Apple, Inc. | Unix Shell Script (bash) |
| 26 | BASHRC | The GNU Project | Bash Non-Interactive Login Shell Format |
| 27 | BASH_HISTORY | The GNU Project | Bash History Format |
| 28 | BASH_LOGIN | GNU Project | Unix Shell Script (bash) |
| 29 | BASH_LOGOUT | GNU Project | Unix Shell Script (bash) |
| 30 | BASH_PROFILE | The GNU Project | Bash Interactive Login Shell Format |
| 31 | BAT | Microsoft | Batch Format (executable) |
| 32 | BAU | Sun Microsystems | Apache OpenOffice AutoText Format |
| 33 | BAY | Casio | Casio RAW Image |
| 34 | BA_ | Microsoft | Renamed BAT Format |
| 35 | BB | Blitz Research | Blitz Source Code Format |
| 36 | BBA | Ubisoft Entertainment S.A. | BlueByte Archive |
| 37 | BBB | Research In Motion | BlackBerry Backup (post 2012) Format |
| 38 | BBFW | Apple, Inc. | ITunes Firmware |
| 39 | BBL | Oren Patashnik | TeX/BibTeX Bibliographic Reference Format |
| 40 | BBLX | Rick Meyers | E-Sword Bible |
| 41 | BBS | N/A | Bulletin Board System Text |
| 42 | BC | BitComet | BitComet Partially Downloaded Format |
| 43 | BC! | BitComet | BitComet Incomplete Format |
| 44 | BCC | Embarcadero Technologies | Borland C++ Format/makefile |
| 45 | BCP | Borland | Borland C++ Makefile |
| 46 | BCR | PVT AG | Map&guide Station List |
| 47 | BDB | Microsoft | Microsoft Works Database Backup Format |
| 48 | BDC | Babylon | Babylon Dictionary Format |
| 49 | BDIC | Google | Chrome Dictionary Format |
| 50 | BDL | Parametric Technology | CoCreate Bundle Format |
| 51 | BDMV | Blu-ray Disc Association | Blu-ray Information Format |
| 52 | BDR | Microsoft | Exchange Non-Delivery Report Body Format |
| 53 | BDSGROUP | Embarcadero Technologies, Inc. | BDS Project Group |
| 54 | BDSPROJ | Embarcadero Technologies | BDS Project Format |
| 55 | BDT | ABBYY | Lingvo Dictionary |
| 56 | BEL | N/A | Belon Compressed Archive |
| 57 | BEPF | N/A | Adobe Big Endian Prebuilt Format |
| 58 | BET | N/A | BETA Source Format |
| 59 | BETA | N/A | Beta programming language source code |
| 60 | BF | Cryo Interactive Entertainment | CryoBF Game Data Format |
| 61 | BFX | Cheyenne | Bitware Fax Document |
| 62 | BGA | N/A | OS/2 Graphic Array |
| 63 | BGL | Microsoft | Flight Simulator Scenery Format |
| 64 | BGT | FKJ Software | Graphics Accounts Data Format |
| 65 | BH | ZipTV | BlakHole Archive |
| 66 | BIBTEX | Sublime HQ Pty Ltd | BibTeX Document |
| 67 | BIG | Electronic Arts | Electronic Arts Game Data Format |
| 68 | BIK | RAD Game Tools | BINK Video Format |
| 69 | BIL | ESRI | ESRI BIL Format |
| 70 | BIMAGE | N/A | id Tech texture data |
| 71 | BIMX | Graphisoft | ArchiCAD BIMx 3D Scene |
| 72 | BIN | N/A | Binary Disc Image |
| 73 | BIT | Xilinx | Xilinx Bitstream Format |
| 74 | BK! | Corel Corporation | Corel WordPerfect Document Backup |
| 75 | BK1 | Autodesk | Autodesk Backup Format |
| 76 | BK2 | Microsoft | Windows Indexing Service Data Format |
| 77 | BK3 | Corel Corporation | Corel WordPerfect Document Backup |
| 78 | BK5 | Corel Corporation | Corel WordPerfect Document Backup |
| 79 | BK6 | Corel Corporation | Corel WordPerfect Document Backup |
| 80 | BK7 | Corel Corporation | Corel WordPerfect Document Backup |
| 81 | BK8 | Corel Corporation | Corel WordPerfect Document Backup |
| 82 | BK9 | Corel Corporation | Corel WordPerfect Document Backup |
| 83 | BKD | N/A | Book Library Local Dos Exploit |
| 84 | BKF | Microsoft | Windows Backup Utility Format |
| 85 | BKI | IBM | IBM BookManager Backup Index |
| 86 | BKPI | N/A | Synology Hyper Backup image |
| 87 | BKY | MIT | Bookkey Bookmark/keyword Data |
| 88 | BLA | Adobe Systems Incorporated | Adobe Black Colour Separation |
| 89 | BLB | Dreamworks Interactive | Blob Data Format |
| 90 | BLEND | The Blender Foundation | Blender 3D Data Format |
| 91 | BLF | Microsoft | Microsoft Windows Vista And Windows 7 Registry Format |
| 92 | BLIF | N/A | Berkeley Logic Interchange Format |
| 93 | BLM | N/A | Eurolink Comma Separated Value |
| 94 | BLN | Golden Software | Golden Software Blanking Format |
| 95 | BLP | Blizzard Entertainment | Blizzard Texture Format |
| 96 | BLV | Ubisoft Entertainment S.A. | Might And Magic 6/7 Dungeon Level Geometry |
| 97 | BM | N/A | X Windows System Bitmap Image |
| 98 | BM2 | DynaVox Mayer-Johnson | Subspace Bitmap Format |
| 99 | BMC | Microsoft | Bitmap Cache Format |
| 100 | BMD | WEBZEN | MU Online Game Data Format |
| 101 | BMD6MODEL | N/A | id Tech 6 model |
| 102 | BMF | Corel | Binary Material Format |
| 103 | BML | N/A | Bean Markup Language Format |
| 104 | BMODEL | N/A | id Tech 6 model |
| 105 | BMP | Microsoft | Bitmap Image Format |
| 106 | BMPW | N/A | Blender GIS world data |
| 107 | BMU | N/A | BioWare Music Unit |
| 108 | BNA | Golden Software | Atlas Boundary Format |
| 109 | BND | JoWooD Entertainment AG | Neighbours From Hell Game Archive |
| 110 | BNDL | N/A | Game Data Bundle Format |
| 111 | BNDLXML5 | N/A | Middle Earth: Shadow of Mordor game data |
| 112 | BNI | Blizzard Entertainment, Inc. | Blizzard Battle.Net Icon |
| 113 | BNK | Eden Games | Test Drive Unlimited Data Package |
| 114 | BNS | Valve | Portal Script Format |
| 115 | BNT | MindArk PE AB. | Entropia Universe Game Archive |
| 116 | BNX | N/A | Board Neutral Exchange data |
| 117 | BOD | Egosoft | X3 Reunion Ship |
| 118 | BOE | Microsoft Corporation | Microsoft Outlook Express Backup |
| 119 | BOM | Apple | Mac OS X Bill Of Materials Format |
| 120 | BONK | Bonk | Bonk Audio Format |
| 121 | BOOK | Adobe Systems | FrameMaker Book Format |
| 122 | BOOTEFISIGNATURE | Apple, Inc. | Bootefisignature Mac OS X System |
| 123 | BOZ | Julian Seward | Bzip Compressed Archive |
| 124 | BPG | Embarcadero Technologies | Borland Project Group |
| 125 | BPK | Nero | Nero SecurDisc Public Key Format |
| 126 | BPL | Subsite Electronics | AutoCAD Batch Plot Format |
| 127 | BPMN | KAISHA-Tec Co. Ltd | Avantage Template |
| 128 | BPWX | N/A | Blender GIS world data |
| 129 | BR25 | N/A | BMW iDrive multimedia data |
| 130 | BR27 | N/A | BMW iDrive multimedia data |
| 131 | BR28 | N/A | BMW iDrive multimedia data |
| 132 | BR29 | N/A | BMW iDrive multimedia data |
| 133 | BR31 | N/A | BMW iDrive multimedia data |
| 134 | BR32 | N/A | BMW iDrive multimedia data |
| 135 | BR48 | N/A | BMW iDrive multimedia data |
| 136 | BRD | CadSoft | EAGLE Circuit Board Format |
| 137 | BREP | Open CASCADE | 3D Model |
| 138 | BRF | N/A | Braille Ready Format |
| 139 | BRG | Bentley Systems | ProjectWise User Settings Format |
| 140 | BRIDGECACHET | Adobe Systems Incorporated | Adobe Bridge Cache |
| 141 | BRIDGESUPPORT | Apple, Inc. | Bridgesupport Mac OS X Format Extension |
| 142 | BRK | Dialogic | Brooktrout Fax Format |
| 143 | BRN | BrainStorm Software | BrainStorm Data Format |
| 144 | BROWSER | Microsoft | ASP.NET Browser Definition Format |
| 145 | BRPX | Rick Meyers | E-sword Bible Reading Plan |
| 146 | BRX | Qualcomm | BREW Application Resource Format |
| 147 | BS2 | Parallax | BASIC Stamp 2 Code Format |
| 148 | BS4 | BeamYourScreen | Mikogo Session Video Recording |
| 149 | BSA | Bethesda Softworks | Bethesda Softworks Archive |
| 150 | BSB | Pitney Bowes Software Inc. | MapInfo Sea Chart Format |
| 151 | BSCOMP | N/A | Bootstrap component |
| 152 | BSDESIGN | Zine | Bootstrap Studio Website Design |
| 153 | BSDL | IEEE | Boundary Scan Description Language Format |
| 154 | BSF | N/A | Blu-ray AVC Video Format |
| 155 | BSH | Patrick Niemeyer | BeanShell Script |
| 156 | BSON | 10gen | BSON Binary JSON |
| 157 | BSS | Capcom | Resident Evil Background Images Format |
| 158 | BST | N/A | BibTeX Style Document |
| 159 | BSWX | Microsoft Corporation | Microsoft Office PerformancePoint Server Database |
| 160 | BSZ | bs.global organization | BSplayer Compressed Skin |
| 161 | BTH | Jeppesen Marine, Inc. | Bathy Recorder Data |
| 162 | BTK | Procedimientos-Uno, S.L. | CLwin Tekton Database |
| 163 | BTKEY | BitTorrent, Inc. | BitTorrent License Key |
| 164 | BTM | Microsoft | BizTalk Map Format |
| 165 | BTN | Lincoln Beach Software | Just Buttons Animated Bitmap Image Format |
| 166 | BTOA | N/A | Binary-to-ASCII Encoded Format |
| 167 | BTPROJ | N/A | Microsoft BizTalk Server project |
| 168 | BTREE | Apple, Inc. | Apple Mac OS HFS+ B-tree |
| 169 | BTSEARCH | BitTorrent | BitTorrent Search Engine Format |
| 170 | BUD | Microsoft | Binary Printer Description Format |
| 171 | BUFFEREDIMAGE | Oracle Corporation | Java Class |
| 172 | BUILD | SourceForge | NAnt Build Tool |
| 173 | BUILDER | N/A | Builder Script |
| 174 | BUILDPATH | Eclipse | Eclipse XML Build Path Format |
| 175 | BUM | N/A | Poser Bump Formats Image Format |
| 176 | BUN | Roland | Cakewalk Bundle Format |
| 177 | BUNDLE | Apple | Mac OS X Application Plug-in |
| 178 | BUNDLEDMESH | Electronic Arts, Inc. | Battlefield Bundled Mesh |
| 179 | BUP | McAfee | DVD IFO Backup Format |
| 180 | BUR | Fluffy Smoke Entertainment | BuRg3r Source Code Format |
| 181 | BV1 | Corel Corporation | Corel WordPerfect Overflow |
| 182 | BV2 | Corel Corporation | Corel WordPerfect Overflow |
| 183 | BV3 | Corel Corporation | Corel WordPerfect Overflow |
| 184 | BV4 | Corel Corporation | Corel WordPerfect Overflow |
| 185 | BV5 | Corel Corporation | Corel WordPerfect Overflow |
| 186 | BV6 | Corel Corporation | Corel WordPerfect Overflow |
| 187 | BV7 | Corel Corporation | Corel WordPerfect Overflow |
| 188 | BV8 | Corel Corporation | Corel WordPerfect Overflow |
| 189 | BV9 | Corel Corporation | Corel WordPerfect Overflow |
| 190 | BVH | Biovision | Biovision Hierarchy Animation Format |
| 191 | BVY | N/A | Breevy text snippet |
| 192 | BW | Paul Haeberli | Silicon Graphics Image |
| 193 | BW1 | Byteworx | FMEA Database |
| 194 | BWC | Black Hills Software | BeadWizard Color Palette |
| 195 | BWF | N/A | Broadcast Wave Format |
| 196 | BWI | VSO Software | BlindWrite CD/DVD Disc Image |
| 197 | BWT | VSO Software | BlindWrite 4 Disk Image |
| 198 | BXZ | N/A | Generic |
| 199 | BYU | BYU | Movie.BYU Geometry Format |
| 200 | BZ | N/A | Bzip Compressed Format |
| 201 | BZ2 | Julian Seward | Bzip2 Compressed Format |
| 202 | BZA | N/A | IZArc BGA Archive |
| 203 | BZIP | N/A | Bzip Compressed Archive |
| 204 | BZIP2 | Bzip | Bzip2 Compressed Archive |
| 205 | B~K | N/A | Microsoft Windows 3.x data |
