file-type

Detect the file type of a Buffer/Uint8Array/ArrayBuffer

The file type is detected by checking the magic number of the buffer.

This package is for detecting binary-based file formats, not text-based formats like .txt, .csv, .svg, etc.

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Install

$ npm install file-type

Usage

Node.js

Determine file type from a file:

const FileType = require('file-type');

(async () => {
	console.log(await FileType.fromFile('Unicorn.png'));
	//=> {ext: 'png', mime: 'image/png'}
})();

Determine file type from a Buffer, which may be a portion of the beginning of a file:

const FileType = require('file-type');
const readChunk = require('read-chunk');

(async () => {
	const buffer = readChunk.sync('Unicorn.png', 0, 4100);

	console.log(await FileType.fromBuffer(buffer));
	//=> {ext: 'png', mime: 'image/png'}
})();

Determine file type from a stream:

const fs = require('fs');
const FileType = require('file-type');

(async () => {
	const stream = fs.createReadStream('Unicorn.mp4');

	console.log(await FileType.fromStream(stream));
	//=> {ext: 'mp4', mime: 'video/mp4'}
}
)();

The stream method can also be used to read from a remote location:

const got = require('got');
const FileType = require('file-type');

const url = 'https://upload.wikimedia.org/wikipedia/en/a/a9/Example.jpg';

(async () => {
	const stream = got.stream(url);

	console.log(await FileType.fromStream(stream));
	//=> {ext: 'jpg', mime: 'image/jpeg'}
})();

Another stream example:

const stream = require('stream');
const fs = require('fs');
const crypto = require('crypto');
const FileType = require('file-type');

(async () => {
	const read = fs.createReadStream('encrypted.enc');
	const decipher = crypto.createDecipheriv(alg, key, iv);

	const fileTypeStream = await FileType.stream(stream.pipeline(read, decipher));

	console.log(fileTypeStream.fileType);
	//=> {ext: 'mov', mime: 'video/quicktime'}

	const write = fs.createWriteStream(`decrypted.${fileTypeStream.fileType.ext}`);
	fileTypeStream.pipe(write);
})();

Browser

const FileType = require('file-type/browser');

const url = 'https://upload.wikimedia.org/wikipedia/en/a/a9/Example.jpg';

(async () => {
	const response = await fetch(url);
	const fileType = await FileType.fromStream(response.body);

	console.log(fileType);
	//=> {ext: 'jpg', mime: 'image/jpeg'}
})();

const FileType = require('file-type/browser');

(async () => {
	const blob = new Blob(['<?xml version="1.0" encoding="ISO-8859-1" ?>'], {
		type: 'plain/text',
		endings: 'native'
	});

	console.log(await FileType.fromBlob(blob));
	//=> {ext: 'txt', mime: 'plain/text'}
})();

API

FileType.fromBuffer(buffer)

Detect the file type of a Buffer, Uint8Array, or ArrayBuffer.

The file type is detected by checking the magic number of the buffer.

If file access is available, it is recommended to use FileType.fromFile() instead.

Returns a Promise for an object with the detected file type and MIME type:

• ext - One of the supported file types
• mime - The MIME type

Or undefined when there is no match.

buffer

Type: Buffer | Uint8Array | ArrayBuffer

A buffer representing file data. It works best if the buffer contains the entire file, it may work with a smaller portion as well.

FileType.fromFile(filePath)

Detect the file type of a file path.

The file type is detected by checking the magic number of the buffer.

Returns a Promise for an object with the detected file type and MIME type:

• ext - One of the supported file types
• mime - The MIME type

Or undefined when there is no match.

filePath

Type: string

The file path to parse.

FileType.fromStream(stream)

Detect the file type of a Node.js readable stream.

The file type is detected by checking the magic number of the buffer.

Returns a Promise for an object with the detected file type and MIME type:

• ext - One of the supported file types
• mime - The MIME type

Or undefined when there is no match.

stream

Type: stream.Readable

A readable stream representing file data.

FileType.fromTokenizer(tokenizer)

Detect the file type from an ITokenizer source.

This method is used internally, but can also be used for a special "tokenizer" reader.

A tokenizer propagates the internal read functions, allowing alternative transport mechanisms, to access files, to be implemented and used.

Returns a Promise for an object with the detected file type and MIME type:

• ext - One of the supported file types
• mime - The MIME type

Or undefined when there is no match.

An example is @tokenizer/http, which requests data using HTTP-range-requests. A difference with a conventional stream and the tokenizer, is that it can ignore (seek, fast-forward) in the stream. For example, you may only need and read the first 6 bytes, and the last 128 bytes, which may be an advantage in case reading the entire file would take longer.

const {makeTokenizer} = require('@tokenizer/http');
const FileType = require('file-type');

const audioTrackUrl = 'https://test-audio.netlify.com/Various%20Artists%20-%202009%20-%20netBloc%20Vol%2024_%20tiuqottigeloot%20%5BMP3-V2%5D/01%20-%20Diablo%20Swing%20Orchestra%20-%20Heroines.mp3';

(async () => {
	const httpTokenizer = await makeTokenizer(audioTrackUrl);
	const fileType = await FileType.fromTokenizer(httpTokenizer);

	console.log(fileType);
	//=> {ext: 'mp3', mime: 'audio/mpeg'}
})();

Or use @tokenizer/s3 to determine the file type of a file stored on Amazon S3:

const FileType = require('file-type');
const S3 = require('aws-sdk/clients/s3');
const {makeTokenizer} = require('@tokenizer/s3');

(async () => {
	// Initialize the S3 client
	const s3 = new S3();

	// Initialize the S3 tokenizer.
	const s3Tokenizer = await makeTokenizer(s3, {
		Bucket: 'affectlab',
		Key: '1min_35sec.mp4'
	});

	// Figure out what kind of file it is.
	const fileType = await FileType.fromTokenizer(s3Tokenizer);
	console.log(fileType);
})();

Note that only the minimum amount of data required to determine the file type is read (okay, just a bit extra to prevent too many fragmented reads).

tokenizer

Type: ITokenizer

A file source implementing the tokenizer interface.

FileType.stream(readableStream)

Detect the file type of a readable stream.

Returns a Promise which resolves to the original readable stream argument, but with an added fileType property, which is an object like the one returned from FileType.fromFile().

Note: This method is only available using Node.js.

readableStream

Type: stream.Readable

The input stream.

FileType.extensions

Returns a set of supported file extensions.

FileType.mimeTypes

Returns a set of supported MIME types.

Supported file types

• jpg - Joint Photographic Experts Group image
• png - Portable Network Graphics
• apng - Animated Portable Network Graphics
• gif - Graphics Interchange Format
• webp - Web Picture format
• flif - Free Lossless Image Format
• xcf - eXperimental Computing Facility
• cr2 - Canon Raw image file (v2)
• cr3 - Canon Raw image file (v3)
• orf - Olympus Raw image file
• arw - Sony Alpha Raw image file
• dng - Adobe Digital Negative image file
• nef - Nikon Electronic Format image file
• rw2 - Panasonic RAW image file
• raf - Fujifilm RAW image file
• tif - Tagged Image file
• bmp - Bitmap image file
• icns - Apple Icon image
• jxr - Joint Photographic Experts Group extended range
• psd - Adobe Photoshop document
• indd - Adobe InDesign document
• zip - Archive file
• tar - Tarball archive file
• rar - Archive file
• gz - Archive file
• bz2 - Archive file
• zst - Archive file
• 7z - 7-Zip archive
• dmg - Apple Disk Image
• mp4 - MPEG-4 Part 14 video file
• mid - Musical Instrument Digital Interface file
• mkv - Matroska video file
• webm - Web video file
• mov - QuickTime video file
• avi - Audio Video Interleave file
• mpg - MPEG-1 file
• mp1 - MPEG-1 Audio Layer I
• mp2 - MPEG-1 Audio Layer II
• mp3 - Audio file
• ogg - Audio file
• ogv - Audio file
• ogm - Audio file
• oga - Audio file
• spx - Audio file
• ogx - Audio file
• opus - Audio file
• flac - Free Lossless Audio Codec
• wav - Waveform Audio file
• qcp - Tagged and chunked data
• amr - Adaptive Multi-Rate audio codec
• pdf - Portable Document Format
• epub - E-book file
• mobi - Mobipocket
• exe - Executable file
• swf - Adobe Flash Player file
• rtf - Rich Text Format
• woff - Web Open Font Format
• woff2 - Web Open Font Format
• eot - Embedded OpenType font
• ttf - TrueType font
• otf - OpenType font
• ico - Windows icon file
• flv - Flash video
• ps - Postscript
• xz - Compressed file
• sqlite - SQLite file
• nes - Nintendo NES ROM
• crx - Google Chrome extension
• xpi - XPInstall file
• cab - Cabinet file
• deb - Debian package
• ar - Archive file
• rpm - Red Hat Package Manager file
• Z - Unix Compressed File
• lz - Arhive file
• cfb - Compount File Binary Format
• mxf - Material Exchange Format
• mts - Blu-ray Disc Audio-Video MPEG-2 Transport Stream
• wasm - WebAssembly intermediate compiled format
• blend - Blender project
• bpg - Better Portable Graphics file
• docx - Microsoft Word
• pptx - Microsoft Powerpoint
• xlsx - Microsoft Excel
• jp2 - JPEG 2000
• jpm - JPEG 2000
• jpx - JPEG 2000
• mj2 - Motion JPEG 2000
• aif - Audio Interchange file
• odt - OpenDocument for word processing
• ods - OpenDocument for spreadsheets
• odp - OpenDocument for presentations
• xml - eXtensible Markup Language
• heic - High Efficiency Image File Format
• cur - Icon file
• ktx - OpenGL and OpenGL ES textures
• ape - Monkey's Audio
• wv - WavPack
• asf - Advanced Systems Format
• dcm - DICOM Image File
• mpc - Musepack (SV7 & SV8)
• ics - iCalendar
• vcf - vCard
• glb - GL Transmission Format
• pcap - Libpcap File Format
• dsf - Sony DSD Stream File (DSF)
• lnk - Microsoft Windows file shortcut
• alias - macOS Alias file
• voc - Creative Voice File
• ac3 - ATSC A/52 Audio File
• 3gp - Multimedia container format defined by the Third Generation Partnership Project (3GPP) for 3G UMTS multimedia services
• 3g2 - Multimedia container format defined by the 3GPP2 for 3G CDMA2000 multimedia services
• m4v - MPEG-4 Visual bitstreams
• m4p - MPEG-4 files with audio streams encrypted by FairPlay Digital Rights Management as were sold through the iTunes Store
• m4a - Audio-only MPEG-4 files
• m4b - Audiobook and podcast MPEG-4 files, which also contain metadata including chapter markers, images, and hyperlinks
• f4v - ISO base media file format used by Adobe Flash Player
• f4p - ISO base media file format protected by Adobe Access DRM used by Adobe Flash Player
• f4a - Audio-only ISO base media file format used by Adobe Flash Player
• f4b - Audiobook and podcast ISO base media file format used by Adobe Flash Player
• mie - Dedicated meta information format which supports storage of binary as well as textual meta information
• shp - Geospatial vector data format
• arrow - Columnar format for tables of data
• aac - Advanced Audio Coding
• it - Audio module format: Impulse Tracker
• s3m - Audio module format: ScreamTracker 3
• xm - Audio module format: FastTracker 2
• ai - Adobe Illustrator Artwork
• skp - SketchUp
• avif - AV1 Image File Format
• eps - Encapsulated PostScript
• lzh - LZH archive
• pgp - Pretty Good Privacy
• asar - Archive format primarily used to enclose Electron applications
• stl - Standard Tesselated Geometry File Format (ASCII only)
• chm - Microsoft Compiled HTML Help
• 3mf - 3D Manufacturing Format
• jxl - JPEG XL image format

Pull requests are welcome for additional commonly used file types.

The following file types will not be accepted:

• MS-CFB: Microsoft Compound File Binary File Format based formats, too old and difficult to parse:
  • .doc - Microsoft Word 97-2003 Document
  • .xls - Microsoft Excel 97-2003 Document
  • .ppt - Microsoft PowerPoint97-2003 Document
  • .msi - Microsoft Windows Installer
• .csv - Reason.
• .svg - Detecting it requires a full-blown parser. Check out is-svg for something that mostly works.

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Related

• file-type-cli - CLI for this module

Maintainers

• Sindre Sorhus
• Mikael Finstad
• Ben Brook
• Borewit