This package can be used to detect the MIME type and canonical extension by looking for magic numbers. It works by reading a small amount of data from the file (~256 bytes) and binary pattern matching against it's contents.

API Documentation

Detecting a file's type:

iex> FileType.from_path("profile.png")
{:ok, {"png", "image/png"}}

iex> FileType.from_path("contract.docx")
{:ok, {"docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document"}}

Detect a file's type from an IO:

iex> {:ok, file} = File.open("profile.png", [:read, :binary])
{:ok, file}

iex> FileType.from_io(file)
{:ok, {"png", "image/png"}}

The package can be installed by adding file_type to your list of dependencies in mix.exs:

def deps do
  [
    {:file_type, "~> 0.1.0"}
  ]
end

• docx - Microsoft Word Open XML Document
• pptx - PowerPoint Open XML Presentation
• xlsx - Microsoft Excel Open XML Spreadsheet
• doc - Microsoft Word Document
• ppt - PowerPoint Presentation
• xls - Excel Spreadsheet
• pdf - Portable Document Format File
• epub - Open eBook File
• mobi - Mobipocket eBook
• odt - OpenDocument Text Document
• ods - OpenDocument Spreadsheet
• odp - OpenDocument Presentation
• rtf - Rich Text Format File

• jpg - JPEG Image
• png - Portable Network Graphic
• apng - Animated Portable Network Graphic
• gif - Graphical Interchange Format File
• webp - WebP Image
• flif - Free Lossless Image Format File
• cr2 - Canon Raw Image File
• cr3 - Canon Raw 3 Image File
• orf - Olympus RAW File
• arw - Sony Digital Camera Image
• dng - Digital Negative Image File
• nef - Nikon Electronic Format RAW Image
• rw2 - Panasonic RAW Image
• raf - Fuji RAW Image File
• tif - Tagged Image File
• bmp - Bitmap Image File
• icns - macOS Icon Resource File
• jxr - JPEG XR Image
• psd - Adobe Photoshop Document
• dmg - Apple Disk Image
• ico - Icon File
• bpg - BPG Image
• jp2 - JPEG 2000 Core Image File
• jpm - JPEG 2000 Compound Image File Format
• jpx - JPEG 2000 Image File
• heic - High Efficiency Image Format
• cur - Windows Cursor
• ktx - Khronos Texture
• avif - AV1 Image
• dcm - DICOM Image

• mp4 - MPEG-4 Video File
• mkv - Matroska Video File
• webm - WebM Video File
• mov - Apple QuickTime Movie
• avi - Audio Video Interleave File
• mpg - MPEG Video File
• ogv - Ogg Video File
• ogm - Ogg Media File
• flv - Flash Video File
• mts - AVCHD Video File
• mj2 - Motion JPEG 2000 Video Clip
• 3gp - 3GPP Multimedia File
• 3g2 - 3GPP2 Multimedia File
• m4v - iTunes Video File
• m4p - iTunes Music Store Audio File
• f4v - Flash MP4 Video File
• f4p - Adobe Flash Protected Media File

• mp1 - MPEG-1 Layer 1 Audio File
• mp2 - MPEG Layer II Compressed Audio File
• mp3 - MP3 Audio File
• aac - Advanced Audio Coding File
• ogg - Ogg Vorbis Audio File
• oga - Ogg Vorbis Audio File
• spx - Ogg Vorbis Speex File
• opus - Opus Audio File
• flac - Free Lossless Audio Codec File
• wav - WAVE Audio File
• mid - MIDI File
• qcp - PureVoice Audio File
• amr - Adaptive Multi-Rate Codec File
• aif - Audio Interchange File Format
• ape - Monkey's Audio Lossless Audio File
• wv - WavPack Audio File
• mpc - Musepack Compressed Audio File
• dsf - Delusion Digital Sound File
• voc - Creative Labs Audio File
• ac3 - Audio Codec 3 File
• m4a - MPEG-4 Audio File
• m4b - MPEG-4 Audiobook File
• f4a - Adobe Flash Protected Audio File
• f4b - Extension Not Found
• it - Impulse Tracker Module
• s3m - ScreamTracker 3 Module
• xm - Fasttracker 2 Extended Module

• ttf - TrueType Font
• otf - OpenType Font
• woff - Web Open Font Format File
• woff2 - Web Open Font Format 2.0 File
• eot - Embedded OpenType Font

• zip - Zipped File
• tar - Consolidated Unix File Archive
• rar - WinRAR Compressed Archive
• gz - Gnu Zipped Archive
• bz2 - Bzip2 Compressed File
• 7z - 7-Zip Compressed File
• xz - XZ Compressed Archive
• ar - Midtown Madness Data File
• Z - Unix Compressed File
• lz - Lzip Compressed File
• cfb - Compound Binary File
• cab - Windows Cabinet File
• lzh - LZH Compressed File

• indd - Adobe InDesign Document
• skp - SketchUp Document
• blend - Blender 3D Data File
• ics - Calendar File

• exe - Windows Executable File
• rpm - Red Hat Package Manager File
• xpi - Cross-platform Installer Package
• msi - Windows Installer Package
• deb - Debian Software Package

• ogx - Ogg Vorbis Multiplexed Media File
• swf - Shockwave Flash Movie
• sqlite - SQLite Database File
• nes - Nintendo (NES) ROM File
• crx - Chrome Extension
• mxf - Material Exchange Format File
• wasm - WebAssembly Binary File
• xml - XML File
• glb - STK Globe File
• pcap - Packet Capture Data
• lnk - Windows Shortcut
• alias - macOS Alias
• mie - Meta Information Encapsulation
• shp - Shapes File
• arrow - Arrow Columnar Format
• ps - PostScript File
• eps - Encapsulated PostScript File
• pgp - PGP Security Key
• stl - Stereolithography File

$ mix benchmark

Most files can be detected with a single binary pattern match. To contribute support for new file type:

1. Find an example file. Please make sure you have the rights to use this file.
2. Register the fixture in test/file_type/integration_test.exs.
3. Write some code to detect the file's type in lib/file_type/magic.ex.
4. Update the README to include a mention of your new file format.
5. Send a pull request!

Please note that this library is not intended to detect text-based file formats like CSV, JSON, etc.

• file/file - The canonical file-type detection library.
• sindresorhus/file-type - This library is mostly just a port of that library.
• minad/mimemagic - A popular Ruby library for doing the same thing.