| Extension | Summary |
|---|
| .M | MATLAB Source Code File |
| .M12 | Schiller medilog ECG Raw Data File |
| .M1A | MPEG-1 Audio File |
| .M1PG | iFinish Video Clip |
| .M1V | MPEG-1 Video File |
| .M2 | World of Warcraft Model Object |
| .M21 | AXMEDIS MPEG-21 File |
| .M2A | MPEG-1 Layer 2 Audio File |
| .M2P | Maxthon 2 Browser Plugin File |
| .M2S | Maxthon 2 Browser Skin File |
| .M2T | HDV Video File |
| .M2TS | Blu-ray BDAV Video File |
| .M2V | MPEG-2 Video |
| .M3 | Blizzard MDX3 Model File |
| .M3D | DIALux 3D Object File |
| .M3G | Mobile 3D Graphics Program |
| .M3P | Mach3 Plugin File |
| .M3U | Media Playlist File |
| .M3U8 | UTF-8 M3U Playlist File |
| .M4 | Macro Processor Library |
| .M4A | MPEG-4 Audio File |
| .M4B | MPEG-4 Audiobook File |
| .M4E | MPEG-4 Video File |
| .M4P | iTunes Music Store Audio File |
| .M4R | iPhone Ringtone File |
| .M4S | MPEG-DASH Video Segment |
| .M4U | MPEG-4 Playlist |
| .M4V | iTunes Video File |
| .M5P | MachFive Preset File |
| .M64 | Mupen64 Movie File |
| .M77T | MGD77T Data File |
| .MA | Maya Project File |
| .MA1 | Monarch Audio File |
| .MAB | Mozilla Address Book |
| .MABK | Moto Android Backup File |
| .MAC | Application Macro File |
| .MACBIN | Macbinary Encoded File |
| .MAD | Access Module Shortcut |
| .MAE | My Avatar Editor Character File |
| .MAF | Microsoft Access Form |
| .MAFF | Mozilla Archive Format File |
| .MAG | Access Diagram Shortcut File |
| .MAGIC | SlideMagic Presentation File |
| .MAGIK | Magik Source Code File |
| .MAGIWOL | MagiWOL File |
| .MAHJONGTITANSSAVE-MS | Mahjong Titans Saved Game |
| .MAI | Microsoft Mail File |
| .MAILHOST | MSN Mailhost Settings File |
| .MAILPLANELICENSE | Mailplane License File |
| .MAILSTATIONERY | Apple Mail Stationery File |
| .MAILTOLOC | Mail Internet Location File |
| .MAK | Makefile |
| .MAKE | Xcode Makefile Script |
| .MAKEFILE | Makefile |
| .MAKERBOT | MakerBot Print File |
| .MAKO | Mako Template |
| .MAL | MadAppLauncher Configuration File |
| .MAM | Microsoft Access Macro |
| .MAN | Unix Manual |
| .MANI | Mine-imator Project File |
| .MANIFEST | Steam Manifest File |
| .MANM | Vietcong Game Data File |
| .MAP | TECkit Mapping File |
| .MAP16 | Map16 Tile File |
| .MAPIMAIL | Send To Mail Recipient |
| .MAPLET | Maplet World File |
| .MAPSDATA | iOS Maps Data File |
| .MAPX | Mapjects Client Webparts File |
| .MAQ | Microsoft Access Query |
| .MAR | Mozilla Archive |
| .MARKDN | Markdown File |
| .MARKDOWN | Markdown Documentation File |
| .MARS | Adobe MARS File |
| .MARSHAL | Marshal Data Migration Model File |
| .MART | MartView eBook File |
| .MAS | rFactor Track File |
| .MASK | SpeedGrade Color Mask File |
| .MASSEFFECTPROFILE | Mass Effect Player Profile |
| .MASSEFFECTSAVE | Mass Effect Saved Game |
| .MASTER | ASP.NET Master Page |
| .MAT | Microsoft Access Table Shortcut File |
| .MATERIAL | Rigs of Rods Texture Reference File |
| .MATO | Atomic Combat Saved Game |
| .MAU | Media Attachment Unit |
| .MAV | Access View File |
| .MAW | Access Data Access Page |
| .MAX | Action Replay Max Save File |
| .MAXC | 3ds Max Container File |
| .MAZ | Hover! Maze File |
| .MB | Kodak EasyShare Data File |
| .MBA | Martus Bulletin Archive |
| .MBB | Kodak EasyShare Data File |
| .MBBK | ManaBook Book Kit File |
| .MBD | Multimedia Builder Project File |
| .MBF | Microsoft Money Backup File |
| .MBG | Mailbag Assistant Mailbox File |
| .MBI | Multi-Bootable Information File |
| .MBK | MediaTek Backup File |
| .MBL | Logger Pro Data File |
| .MBLOCK | mBlock Project File |
| .MBM | Multi Bitmap File |
| .MBN | Multi Boot Image |
| .MBOX | Email Mailbox File |
| .MBP | Mobipocket Notes File |
| .MBR | Master Boot Record File |
| .MBS | Opera Mailbox File |
| .MBSA | Microsoft Baseline Security Analyzer File |
| .MBT | Blue Card Manager Merit Badge Template File |
| .MBW | MBRWizard Archive |
| .MBX | Outlook Express Mailbox |
| .MBZ | Moodle Backup FIle |
| .MC | Molecular Constructor Molecule File |
| .MC1 | MedCalc Data File |
| .MC2 | MasterCook 5 Cookbook File |
| .MC5 | Poser 5 Material File |
| .MC6 | Poser Material Collection File |
| .MC9 | Mastercam 9 Geometry File |
| .MCA | Minecraft "Anvil" Map File |
| .MCADDON | Minecraft Pack Addon File |
| .MCAL | Monika After Story Calendar File |
| .MCAPM | Minecraft Anvil PocketMine Data File |
| .MCAT | Adobe Lightroom CC Catalog File |
| .MCD | MiniCAD Design File |
| .MCDX | Mathcad Prime Document |
| .MCF | MasterCook 2 Cookbook File |
| .MCFI | Maya Initial Fluid Cache File |
| .MCFP | Maya Fluid Cache Playback File |
| .MCFUNCTION | Minecraft Commands Function File |
| .MCGAME | Minecraft Game Backup File |
| .MCHELP | MadCap DotNet Help File |
| .MCI | Media Control Interface File |
| .MCIF | MacroMolecular Crystallographic Information File |
| .MCL | Windows Media Center Link File |
| .MCLEVEL | Minecraft Map File |
| .MCMAC | MasterCook Mac Document |
| .MCMETA | Minecraft Animation File |
| .MCO | Live Messenger Winks File |
| .MCOLOR | Mine-imator Interface Color File |
| .MCP | CodeWarrior Project |
| .MCPACK | Minecraft Resource Pack File |
| .MCPR | Minecraft Replay Mod Replay |
| .MCR | ePSXe Memory Card File |
| .MCRP | MobyExplorer Encrypted File |
| .MCS | Mathcad Image |
| .MCSERVER | Minecraft Server File |
| .MCSP | My Craft Studio Project File |
| .MCSTRUCTURE | Minecraft Structure Block |
| .MCSX | My Craft Studio Professional File |
| .MCT | Windows Live Messenger Data File |
| .MCTEMPLATE | Minecraft World Template |
| .MCUSW | Nokia Firmware File |
| .MCW | Monitor Calibration Wizard File |
| .MCWORLD | Minecraft World Backup File |
| .MCX | MICRO CADAM-X/6000 Model Data File |
| .MCXE | MedicinesComplete Data File |
| .MCZ | Compressed Poser Material File |
| .MD | Machine summary File |
| .MD0 | Adobe Photoshop Metadata Cache File |
| .MD1 | Alcohol Disk Image Segment 2 |
| .MD2 | Alcohol Disk Image Segment 2 |
| .MD3 | Quake 3 3D Model |
| .MD5 | MD5 Checksum File |
| .MD5.TXT | Message Digest 5 Hash File |
| .MD5ANIM | id Tech 4 Model Animation File |
| .MD5CAMERA | id Tech 4 Model Camera File |
| .MD5MESH | id Tech 4 3D Mesh File |
| .MD8 | GarageCUBE Modul8 Project |
| .MDA | Access Add-in |
| .MDB | Microsoft Access Database |
| .MDBACKUP | iPhone Data Backup File |
| .MDBHTML | Microsoft Access Database HTML File |
| .MDC | Merkaartor Document |
| .MDD | Point Oven Deformation Data File |
| .MDDATA | iPhone Backup File |
| .MDDBS | Manic Digger Database |
| .MDE | ArchiCAD Educational Version Module File |
| .MDEX | MIRCaM Data EXchange File |
| .MDF | Translation Memory Data Find File |
| .MDG | Digital Geometric Model File |
| .MDI | Microsoft Document Imaging File |
| .MDIMPORTER | Metadata Importer |
| .MDINFO | iPhone Backup Information File |
| .MDJ | StarUML Model File |
| .MDL | Flight Simulator Airplane Model |
| .MDL0 | Wii Model File |
| .MDM | Mario Dash Map File |
| .MDMP | Windows Minidump |
| .MDN | Blank Access Database Template |
| .MDOWN | Markdown File |
| .MDP | Visual C++ 5 Workspace File |
| .MDQ | Transformation Extender Database Definition File |
| .MDR | ModPlug Compressed Module |
| .MDS | Media Descriptor Sidecar File |
| .MDSX | MEGA Saved Session |
| .MDT | GeoMedia Access Database Template |
| .MDW | Access Workgroup File |
| .MDX | MDX Source Code File |
| .MDZ | Access Wizard Template |
| .MDZIP | MagicDraw Project Archive |
| .ME | Temporary Delete Me File |
| .ME2MOD | Mass Effect 2 Modification File |
| .MEB | PRO100 3D Interior Catalog Element |
| .MED | RSView Development Project |
| .MEDIA | Security Camera Video |
| .MEF | Mamiya RAW Image |
| .MEG | MEGA Data File |
| .MEGA | MEGAsync Temporary Data File |
| .MEL | Maya Embedded Language File |
| .MELL | Mellel Word Processing File |
| .MELLEL | Mellel Word Processing Document |
| .MEM | FoxPro Variable File |
| .MEML | Minimalist & Extensive Markup Language File |
| .MEMO | Samsung Memo |
| .MENC | Windows Mobile Encrypted File |
| .MENU | macOS Menu Extra |
| .MEO | MEO Encrypted Archive |
| .MEP | Movavi Video Project |
| .MEPS | Movavi Slideshow Maker Project |
| .MEPX | Movavi Video Project |
| .MER | RSView Development Runtime File |
| .MERLIN2 | Merlin Project File |
| .MERLINLICENSE | Merlin License File |
| .MESH | DirectX Mesh File |
| .MESHLIB | Godot Engine Mesh Library File |
| .MET | Presentation Manager Metafile |
| .META | Exient Metadata File |
| .METADATA_NEVER_INDEX | Spotlight Never Index File |
| .MEX | Macro Express File |
| .MF | Java Manifest File |
| .MF4 | ASAM Measurement Data Format File |
| .MFA | Multimedia Fusion Application |
| .MFCRIBBON-MS | MFC Ribbon Definition XML File |
| .MFD | Music Finder Database |
| .MFE | MobileFrame Enterprise Data File |
| .MFI | HDClone MFI Disk Image |
| .MFIL | Blizzard Software Update File |
| .MFL | ModFit LT Analysis Report File |
| .MFO | MediaFace Online Saved File |
| .MFP | MediaFACE Project File |
| .MFS | MetFS Encrypted File System |
| .MFT | MediaFACE Project Template |
| .MFU | MobileFrame Update File |
| .MFV | MobileFrame Device Pack File |
| .MFW | Clickteam Fusion Project |
| .MFX | Multimedia Fusion Extension |
| .MGA | Manga Document |
| .MGC | Microsoft Clip Organizer Media Catalog |
| .MGCB | Equation Illustrator Project File |
| .MGD77 | MGD77 Data File |
| .MGDATABASE | MacGourmet Deluxe Database File |
| .MGF | Materials and Geometry Format |
| .MGK | ImageMagick Configuration File |
| .MGL | Age of Empires 2 Replay File |
| .MGM | MGCSoft Equation Illustrator Macro |
| .MGMF | MindGenius Map File |
| .MGMT | MindGenius 2-3 Template |
| .MGMX | MindGenius XML Map File |
| .MGO | MacGourmet Recipe File |
| .MGOURMET | MacGourmet Deluxe Document |
| .MGOURMET3 | MacGourmet Deluxe 3 Document |
| .MGOURMET4 | MacGourmet Deluxe 4 Document |
| .MGS | MGCSoft Vector Shapes File |
| .MGSPOT | MacGourmet Spotlight MetaData File |
| .MGT | Musicnotes Guitar Guru Song File |
| .MGTHEME | MacGourmet Theme File |
| .MGTX | MindGenius XML Template File |
| .MGV | PSP Video File |
| .MGW | Mr. Game And Watch ROM File |
| .MGX | Age of Empires 2 Expansion Replay File |
| .MHP | Maths Helper Plus File |
| .MHS | Xilinx XPS Hardware Specification File |
| .MHT | MHTML Web Archive |
| .MHTML | MIME HTML File |
| .MI4 | Audio Player Firmware File |
| .MIC | Image Composer File |
| .MID | MapInfo Data File |
| .MIDI | MIDI File |
| .MIF | Management Information Format |
| .MIFF | Magick Image File |
| .MIG | Windows Migration Backup File |
| .MIGRATEDAPLIBRARY | Migrated Aperture Library |
| .MIGRATEDPHOTOLIBRARY | Migrated Photo Library |
| .MII | Wii Virtual Avatar File |
| .MIIGX | Savegame-manager-gx Nintendo Mii |
| .MILK | MilkDrop Winamp Plug-in Preset |
| .MIM | Multi-Purpose Internet Mail Message File |
| .MIME | Multi-Purpose Internet Mail Extension |
| .MIN | MAX Interchange Notation File |
| .MINC | Pokemon Mini Color File |
| .MIND | MindMeister Map File |
| .MINDNODE | MindNode Document |
| .MINE | Minecraft Map File |
| .MINESWEEPERSAVE-MS | Minesweeper Saved Game |
| .MINI2SF | Nintendo DS Sound Information File |
| .MINIGSF | Game Boy Advance Song File |
| .MININCSF | NCSF Nintendo DS Audio File |
| .MINIPSF | Miniature PlayStation Sound Format File |
| .MINIPSF2 | Miniature PlayStation Sound Format File |
| .MINISO | Mini Image Destination File |
| .MINIUSF | Nintendo 64 Song File |
| .MINT | Linux Mint Installer File |
| .MIO | WarioWare D.I.Y. Microgame File |
| .MIP | Multiple Image Print File |
| .MIPMAPS | Mipmap Texture File |
| .MIPROJECT | Mine-imator Project |
| .MIR | Mini-Image Ripper Disc Image |
| .MIS | Saved Game Mission File |
| .MISSION | Vega Strike Mission File |
| .MIT | MineEdit Inventory Template File |
| .MIX | MotoGP Game File |
| .MJ2 | Motion JPEG 2000 Video Clip |
| .MJBOOKTEMPLATE | MacJournal Book Template |
| .MJD | Adobe Acrobat MIME Encoded Job Definition File |
| .MJDOC | MacJournal Document |
| .MJK | Question File |
| .MJP | MJPEG Video File |
| .MJPEG | Motion JPEG Video File |
| .MJPG | Motion JPEG Video File |
| .MJS | Node.js ES Module File |
| .MK | Makefile |
| .MK3D | Matroska 3D Video File |
| .MK4 | Schiller medilog ECG Raw Data File |
| .MKA | Matroska Audio File |
| .MKD | Markdown Documentation File |
| .MKS | Matroska Elementary Stream File |
| .MKV | Matroska Video File |
| .ML | ML Source Code File |
| .MLB | Visual FoxPro Library |
| .MLC | MobaLiveCD File |
| .MLK | MasterCook Look File |
| .MLL | Maya Plugin |
| .MLM | MolMeccano File |
| .MLMODEL | Create ML Model |
| .MLP | Meridian Lossless Packing Audio File |
| .MLPKGINSTALL | Support Package Installer File |
| .MLPROJ | Create ML Project |
| .MLS | CrystalPlayer Playlist |
| .MLT | Shotcut Project |
| .MLX | MATLAB Live Script |
| .MM | Objective-C++ Source File |
| .MM6 | Might and Magic 6 Saved Game |
| .MM7 | Might and Magic 7 Saved Game |
| .MM8 | Might and Magic 8 Saved Game |
| .MMA | Master Album Maker Photo Album File |
| .MMAP | MindManager Map File |
| .MMAS | MindManager Map Theme File |
| .MMAT | MindManager Map Template |
| .MMC | Microsoft Media Catalog |
| .MMCOLLECTION | Mail Manager Collection File |
| .MMDC | MediaMonkey Device Configuration File |
| .MME | Multi-Purpose Internet Mail |
| .MMF | Synthetic Music Mobile Application File |
| .MMG | Model Master 3 Axis Flat File |
| .MMIP | MediaMonkey Installation Package |
| .MMJPROJECT | Music Maker JAM Project |
| .MML | FrameMaker Maker Markup Language File |
| .MMLP | Music Macro Language Project |
| .MMM | MiraMon Maps File |
| .MMMACRO | Mini Mouse Macro File |
| .MMMP | MindManager Map Part File |
| .MMMS | MindManager Map Markers File |
| .MMO | Memory Map Overlay File |
| .MMP | Symbian Project Specification File |
| .MMPZ | LMMS Project File |
| .MMRC | MADRIX MIDI Remote Configuration |
| .MMS | Transformation Extender Map Source File |
| .MMU | myPM Merge Data File |
| .MMV | Magnex Firmware File |
| .MMW | AceMoney Money File |
| .MMZ | MiraMon Compressed Map File |
| .MNC | AutoCAD Compiled Menu File |
| .MNG | Multiple-image Network Graphic |
| .MNH | Master Navigator Header File |
| .MNK | My Notes Keeper Notebook |
| .MNL | AutoCAD Menu LISP File |
| .MNM | Character Studio Marker Name File |
| .MNO | Monopoly Saved Game |
| .MNR | AutoCAD Menu Resource File |
| .MNS | AutoCAD Interface Settings File |
| .MNT | FoxPro Menu Memo |
| .MNU | TomTom Menu File |
| .MNV | PlayStation Movie File |
| .MNX | FoxPro Menu |
| .MNY | Microsoft Money File |
| .MO | Machine Object File |
| .MO3 | MO3 Audio File |
| .MOBI | Mobipocket eBook |
| .MOBILECONFIG | Apple Mobile Configuration File |
| .MOBILEPROVISION | Xcode Mobile Provisioning Profile |
| .MOBIRISE | Mobirise Project File |
| .MOD | Fortran Module File |
| .MODD | Sony Video Analysis File |
| .MODE | Coda Syntax Mode File |
| .MODE1V3 | Xcode Project Data File |
| .MODE2V3 | Xcode Project Data File |
| .MODEL | CATIA 3D Model FIle |
| .MODFEM | Femap Model |
| .MODPKG | Minecraft Pocket Manager File |
| .MODULE | Drupal Module File |
| .MOEF | Apple Motion Effect Project Template |
| .MOF | Managed Object Format File |
| .MOFF | Sony Video Data File |
| .MOGG | Multitrack Ogg File |
| .MOGRT | Adobe Motion Graphics Template |
| .MOHO | Moho Animation Project |
| .MOHOACTION | Moho Action Document |
| .MOHOBRUSH | Moho Brush Document |
| .MOHOEXPORT | Moho Export Profile Document |
| .MOHOPROJ | Moho Document Data File |
| .MOHOSTYLE | Moho Style Document |
| .MOI | MOI Video File |
| .MOL | MDL Molfile |
| .MOL2 | SYBYL MOL2 File |
| .MOM | Managed Object Model |
| .MOMMA | Offspring Fling Replay File |
| .MONEY | Money Data File |
| .MONEYWELL | MoneyWell Account File |
| .MONSTER | D&D 5e Statblock Generator Monster File |
| .MONTAGE | Montage Screenplay File |
| .MOOV | Apple QuickTime Movie |
| .MOS | Leaf Camera RAW File |
| .MOSAIC | MacOSaiX Mosaic File |
| .MOT | LightWave Motion File |
| .MOTI | Apple Motion Title Project Template |
| .MOTN | Apple Motion Generator Project Template |
| .MOTR | Apple Motion Transition Project Template |
| .MOU | WinMount Compressed File |
| .MOUNTAIN | A Short Hike Saved Game |
| .MOV | Apple QuickTime Movie |
| .MOVIE | Payday Movie File |
| .MOX | Montax Imposer Template Document |
| .MOZ | Mozilla Cache File |
| .MOZLZ4 | Compressed Firefox User Profile Data File |
| .MP | LaTeX MetaPost File |
| .MP1 | MPEG-1 Layer 1 Audio File |
| .MP10 | Multisim 10 Project File |
| .MP11 | Multisim 11 Project File |
| .MP12 | Multisim 12 Project |
| .MP13 | Multisim 13 Project |
| .MP14 | Multisim 14 Project |
| .MP2 | Heroes of Might and Magic II Map File |
| .MP21 | MPEG-21 Multimedia File |
| .MP2M | Max Payne 2 Mod File |
| .MP2S | Max Payne 2 Saved Game |
| .MP2V | MPEG-2 Video File |
| .MP3 | MP3 Audio File |
| .MP4 | MPEG-4 Video File |
| .MP4.INFOVID | Parrot AR Drone and Gyro Flyer Video |
| .MP4V | MPEG-4 Video |
| .MP7 | Multisim 7 Project File |
| .MP8 | Multisim 8 Project |
| .MP9 | Multisim 9 Project File |
| .MPA | MPEG-2 Audio File |
| .MPB | MyPhoneExplorer Backup File |
| .MPC | Electronic Arts MPCh Video File |
| .MPCPL | Media Player Classic Playlist |
| .MPD | Microsoft Project Database |
| .MPDCONF | Music Player Daemon File |
| .MPDP | MixPad Project File |
| .MPE | MPEG Movie File |
| .MPEG | MPEG Video |
| .MPEG2 | MPEG-2 Video File |
| .MPEG4 | MPEG-4 File |
| .MPF | Microsoft Media Package FIle |
| .MPG | MPEG Video File |
| .MPG2 | MPEG-2 Video File |
| .MPG4 | MPEG-4 Video File |
| .MPGA | MPEG-1 Layer 3 Audio File |
| .MPGINDEX | Adobe MPEG Index File |
| .MPH | Photostory Deluxe Project |
| .MPI | InstallJammer Project File |
| .MPJ | messiahStudio Project File |
| .MPK | ArcGIS Map Package |
| .MPKG | Meta Package File |
| .MPKT | MOPEKS Trial File |
| .MPL | MPL2 Subtitles File |
| .MPLS | Blu-ray Movie Playlist File |
| .MPM | Max Payne Modfication File |
| .MPN | Mophun Video Game |
| .MPO | Multi Picture Object File |
| .MPP | Microsoft Project File |
| .MPPZ | MagicPlot Project File |
| .MPQ | Blizzard Mo'PaQ File |
| .MPQE | Blizzard Encrypted Mo'PaQ File |
| .MPR | FoxPro Generated Menu Program |
| .MPROJ | Mine-imator Project |
| .MPROJECT | Merlin Project |
| .MPS | Pocket Streets Map File |
| .MPSUB | MPlayer Subtitles File |
| .MPT | Microsoft Project Template |
| .MPU | MPEG Layer 3 Audio File |
| .MPV | MPEG Elementary Stream Video File |
| .MPW | Microsoft Project Workspace File |
| .MPWS | MathPiper Worksheet |
| .MPX | FoxPro Compiled Program Menu |
| .MPZ | Red Eclipse Map File |
| .MPZIP | Multisim Pack File |
| .MP_ | Mobile Phone Sound File |
| .MQ | Message Queuing Message Log File |
| .MQ4 | MQL4 Source Code File |
| .MQ5 | MQL5 Source Code File |
| .MQH | MetaTrader Include File |
| .MQO | Metasequoia Document |
| .MQV | Sony Movie Format File |
| .MRB | Multiple Resolution Bitmap File |
| .MRC | mIRC Script File |
| .MRF | Mouse Recorder File |
| .MRG | MySQL Merge File |
| .MRIMG | Macrium Reflect Disk Image |
| .MRK | DPOF Auto Print Order File |
| .MRML | 3D Slicer Scene summary File |
| .MRP | Mythroad Platform File |
| .MRS | GunZ Game Data File |
| .MRSN | Mersenne Source Code File |
| .MRT | Stimulsoft Report File |
| .MRW | Minolta Raw Image File |
| .MRXS | MIRAX Virtual Slide File |
| .MRY | Tomboy Industrees Memory File |
| .MS | 3ds Max Script File |
| .MS-ONE-STUB | Microsoft OneNote Stub |
| .MS-TNEF | MS Transport Neutral Encapsulation Format |
| .MS1 | VirtualBus Map File |
| .MS10 | Multisim 10 Circuit Design File |
| .MS11 | Multisim 11 Circuit Design File |
| .MS12 | Multisim 12 Circuit Design File |
| .MS13 | Multisim 13 Circuit Design File |
| .MS14 | Multisim 14 Circuit Design File |
| .MS3D | MilkShape 3D Model |
| .MS7 | Multisim 7 Circuit Design File |
| .MS8 | Multisim 8 Circuit Design File |
| .MS9 | Multisim 9 Circuit Design File |
| .MSB | Oracle Binary Message File |
| .MSBT | Message Studio Binary Text File |
| .MSC | Microsoft Management Console Snap-in Control File |
| .MSCT | MOPEKS Script File |
| .MSCX | MuseScore Music Score File |
| .MSCZ | MuseScore Compressed Score File |
| .MSD | Map Service Definition File |
| .MSDVD | Windows DVD Maker Project File |
| .MSE | 3ds Max Encrypted MAXScript File |
| .MSF | Mail Summary File |
| .MSG | Fallout Message File |
| .MSH | Orbiter 3D Mesh File |
| .MSH1XML | Monad Display Configuration File |
| .MSHA | Microsoft Help Asset File |
| .MSHC | Microsoft Help Container File |
| .MSHI | Microsoft Help Index File |
| .MSI | Windows Installer Package |
| .MSIF | MyLabel Designer Deluxe Data File |
| .MSIM | mSecure Password Manager Backup File |
| .MSIX | MSIX Installer Package |
| .MSIXBUNDLE | Windows 10 App Bundle |
| .MSIXUPLOAD | Windows 10 App Upload Bundle |
| .MSK | Paint Shop Pro Mask File |
| .MSKN | MediaMonkey Skin File |
| .MSL | Mapping Specification Language File |
| .MSM | Windows Installer Merge Module |
| .MSMPL_ALL | Korg microSAMPLER Backup File |
| .MSMPL_BANK | Korg microSAMPLER Bank Data File |
| .MSN | Host Blocking File |
| .MSO | Inline E-mail Attachment |
| .MSP | MaxScript Page File |
| .MSPROJ | Message Studio Project |
| .MSPX | Microsoft ASP.NET Web Page |
| .MSRCINCIDENT | Windows Remote Assistance Invitation File |
| .MSS | Microprocessor Software Specification File |
| .MSSTYLE | Windows XP Unsigned Style |
| .MSSTYLES | Windows XP Style |
| .MST | Corel Presentations Master Template File |
| .MSTXT | Message Studio Text File |
| .MSU | Windows Vista Update Package |
| .MSV | Memory Stick Voice File |
| .MSW | Painter Color Mixer Swatches File |
| .MSWMM | Windows Movie Maker Project |
| .MT2 | MadTracker 2 Module |
| .MT2S | MPEG-2 Transport Stream File |
| .MT9 | MT9 Audio File |
| .MTA | Samsung AllShare Metadata File |
| .MTC | Make the Cut! Project |
| .MTD | Musicnotes Digital Sheet Music File |
| .MTE | MadTracker 2 Envelope |
| .MTF | Translation Memory Translations File |
| .MTFF | MadgeTech Data Logger Report |
| .MTGL | Maltego Graph |
| .MTH | Derive Math File |
| .MTHD | MOPEKS Method File |
| .MTI | MadTracker Instrument |
| .MTL | OBJ Material Template Library File |
| .MTM | MultiTracker Module |
| .MTO | FastCAM MTO Text File |
| .MTP | MadTracker 2 Pattern |
| .MTQ | Mustaq Data File |
| .MTS | AVCHD Video File |
| .MTT | MetadataTouch Template |
| .MTV | MTV Video Format File |
| .MTW | Minitab Worksheet File |
| .MTX | MadTracker 2 Extension |
| .MTXT | MOPEKS Text File |
| .MTZ | MIUI Theme |
| .MU | Kerbal Space Program Mesh File |
| .MU3 | Myriad Packed Musical Score |
| .MUD | Textease Multi User Database |
| .MUF | Alpha Five License File |
| .MUI | Multilingual User Interface File |
| .MUI_CCCD5AE0 | Hid User Library |
| .MUL | Deus Ex: HR Multiplexed Audio File |
| .MULIB | Muse Library File |
| .MUM | Windows Vista Update Package |
| .MUN | Windows System Resource Archive |
| .MUP | Music Publisher Score |
| .MUS | Electronic Arts Game Music File |
| .MUSA | Aleph One Music File |
| .MUSE | Adobe Muse Website Project |
| .MUSX | Finale Notation File |
| .MUX | Myriad Stand-Alone Music Score |
| .MUZ | MUZ Audio File |
| .MV | MivaScript File |
| .MVC | MivaScript Compiled File |
| .MVD | MindView OS X Document |
| .MVDX | MindView Windows Document |
| .MVE | Interplay MVE Video File |
| .MVEX | Muvee autoProducer 6 Project File |
| .MVG | Magick Vector Graphics File |
| .MVI | AutoCAD Movie Command File |
| .MVM | Photostory Deluxe Slideshow |
| .MVP | MoviePlus Project File |
| .MVR | IBM HotMedia Multimedia File |
| .MVS | Microchip Verification Specification File |
| .MVTX | MindView Template |
| .MVX | Multimedia Fusion Movement Extension |
| .MVY | Video easy Project File |
| .MV_ | Movie Edit Pro Movie Backup File |
| .MW | Maple Worksheet |
| .MWAND | GarageBand MagicMentor Template |
| .MWB | MySQL Workbench Document |
| .MWD | MyWorkDrive Client Shortcut File |
| .MWF | Translation Memory Word Find File |
| .MWL | Super Mario World Level |
| .MWLIC | MoneyWell License File |
| .MWM | Space Engineers 3D Model File |
| .MWP | Lotus Word Pro SmartMaster File |
| .MWPS | Need for Speed: Most Wanted Car Attributes File |
| .MWS | MWave DSP Synth Instrument Extract |
| .MWX | MapGuide Author Map Window XML File |
| .MX | Mathematica Serialized Package File |
| .MX2 | Heroes of Might and Magic II Expansion Map File |
| .MX3 | Mixcraft 3 Audio Project |
| .MX4 | Mixcraft 4 Audio Project |
| .MX5 | Mixcraft 5 Audio Project |
| .MX5TEMPLATE | Mixcraft 5 Audio Project Template |
| .MXAD | Mandelbrot Explorer All Data File |
| .MXADDON | Maxthon Add-On File |
| .MXC2 | MAGIX Cache File |
| .MXCS | Mandelbrot Explorer Color Scheme File |
| .MXD | ArcGIS Map Document |
| .MXDIC | Maxthon Dictionary File |
| .MXE | Macro Express Playable Macro |
| .MXF | Maxis Font File |
| .MXFR | Mandelbrot Explorer Fractal Region File |
| .MXG | Miinoto Exchangeable Group File |
| .MXI | Maxwell Image |
| .MXL | Compressed MusicXML File |
| .MXLIFF | Memsource XLIFF Localization File |
| .MXM | Maxwell Material File |
| .MXMF | Mobile XMF Ringtone File |
| .MXML | Flex MXML Component |
| .MXN | Miinoto Exchangeable Note File |
| .MXP | Adobe Extension Package |
| .MXPRJ | Maschine 2 Project |
| .MXS | Painter Color Mixer Pad File |
| .MXSKIN | Maxthon Skin File |
| .MXT | ArcGIS Map Template |
| .MXV | MAGIX Video File |
| .MYAPP | Visual Studio Application XML File |
| .MYCOLORS | Stardock MyColors Theme File |
| .MYD | MySQL Database Data File |
| .MYDOCS | Send To My Documents |
| .MYI | MySQL MyISAM Index File |
| .MYL | MyLogo Maker Image |
| .MYM | MyMenuify Wii Theme File |
| .MYNOTESBACKUP | Keep My Notes Backup |
| .MYO | AccountEdge Company File |
| .MYR | Myriad Music File |
| .MYS | Vineyard Captured Video File |
| .MZ2 | MasterCook Recipe |
| .MZP | WinArchiver Mountable Archive |
| .MZZ | Microsoft .NET Download Package |