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.
We accept contributions for commonly used modern file formats, not historical or obscure ones. Open an issue first for discussion.
npm install file-typeThis package is a ESM package. Your project needs to be ESM too. Read more.
If you use it with Webpack, you need the latest Webpack version and ensure you configure it correctly for ESM.
Determine file type from a file:
import {fileTypeFromFile} from 'file-type';
console.log(await fileTypeFromFile('Unicorn.png'));
//=> {ext: 'png', mime: 'image/png'}Determine file type from a Buffer, which may be a portion of the beginning of a file:
import {fileTypeFromBuffer} from 'file-type';
import {readChunk} from 'read-chunk';
const buffer = await readChunk('Unicorn.png', {length: 4100});
console.log(await fileTypeFromBuffer(buffer));
//=> {ext: 'png', mime: 'image/png'}Determine file type from a stream:
import fs from 'node:fs';
import {fileTypeFromStream} from 'file-type';
const stream = fs.createReadStream('Unicorn.mp4');
console.log(await fileTypeFromStream(stream));
//=> {ext: 'mp4', mime: 'video/mp4'}The stream method can also be used to read from a remote location:
import got from 'got';
import {fileTypeFromStream} from 'file-type';
const url = 'https://upload.wikimedia.org/wikipedia/en/a/a9/Example.jpg';
const stream = got.stream(url);
console.log(await fileTypeFromStream(stream));
//=> {ext: 'jpg', mime: 'image/jpeg'}Another stream example:
import stream from 'node:stream';
import fs from 'node:fs';
import crypto from 'node:crypto';
import {fileTypeStream} from 'file-type';
const read = fs.createReadStream('encrypted.enc');
const decipher = crypto.createDecipheriv(alg, key, iv);
const streamWithFileType = await fileTypeStream(stream.pipeline(read, decipher));
console.log(streamWithFileType.fileType);
//=> {ext: 'mov', mime: 'video/quicktime'}
const write = fs.createWriteStream(`decrypted.${streamWithFileType.fileType.ext}`);
streamWithFileType.pipe(write);import {fileTypeFromStream} from 'file-type';
const url = 'https://upload.wikimedia.org/wikipedia/en/a/a9/Example.jpg';
const response = await fetch(url);
const fileType = await fileTypeFromStream(response.body);
console.log(fileType);
//=> {ext: 'jpg', mime: 'image/jpeg'}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 fileTypeFromFile() instead.
Returns a Promise for an object with the detected file type:
ext- One of the supported file typesmime- The MIME type
Or undefined when there is no match.
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.
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:
ext- One of the supported file typesmime- The MIME type
Or undefined when there is no match.
Type: string
The file path to parse.
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:
ext- One of the supported file typesmime- The MIME type
Or undefined when there is no match.
Type: stream.Readable
A readable stream representing file data.
Detect the file type of a Blob.
The file type is detected by checking the magic number of the buffer.
Returns a Promise for an object with the detected file type:
ext- One of the supported file typesmime- The MIME type
Or undefined when there is no match.
import {fileTypeFromBlob} from 'file-type';
const blob = new Blob(['<?xml version="1.0" encoding="ISO-8859-1" ?>'], {
type: 'text/plain',
endings: 'native'
});
console.log(await fileTypeFromBlob(blob));
//=> {ext: 'txt', mime: 'text/plain'}Type: Blob
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:
ext- One of the supported file typesmime- 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.
import {makeTokenizer} from '@tokenizer/http';
import {fileTypeFromTokenizer} from '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';
const httpTokenizer = await makeTokenizer(audioTrackUrl);
const fileType = await fileTypeFromTokenizer(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:
import S3 from 'aws-sdk/clients/s3';
import {makeTokenizer} from '@tokenizer/s3';
import {fileTypeFromTokenizer} from 'file-type';
// 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 fileTypeFromTokenizer(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).
Type: ITokenizer
A file source implementing the tokenizer interface.
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 fileTypeFromFile().
This method can be handy to put in between a stream, but it comes with a price.
Internally stream() builds up a buffer of sampleSize bytes, used as a sample, to determine the file type.
The sample size impacts the file detection resolution.
A smaller sample size will result in lower probability of the best file type detection.
Note: This method is only available when using Node.js. Note: Requires Node.js 14 or later.
Type: stream.Readable
Type: object
Type: number
Default: 4100
The sample size in bytes.
import got from 'got';
import {fileTypeStream} from 'file-type';
const url = 'https://upload.wikimedia.org/wikipedia/en/a/a9/Example.jpg';
const stream1 = got.stream(url);
const stream2 = await fileTypeStream(stream1, {sampleSize: 1024});
if (stream2.fileType?.mime === 'image/jpeg') {
// stream2 can be used to stream the JPEG image (from the very beginning of the stream)
}Type: stream.Readable
The input stream.
Returns a Set<string> of supported file extensions.
Returns a Set<string> of supported MIME types.
A custom detector is a function that allows specifying custom detection mechanisms.
An iterable of detectors can be provided via the fileTypeOptions argument for the FileTypeParser constructor.
The detectors are called before the default detections in the provided order.
Custom detectors can be used to add new FileTypeResults or to modify return behaviour of existing FileTypeResult detections.
If the detector returns undefined, there are 2 possible scenarios:
- The detector has not read from the tokenizer, it will be proceeded with the next available detector.
- The detector has read from the tokenizer (
tokenizer.positionhas been increased). In that case no further detectors will be executed and the final conclusion is that file-type returns undefined. Note that this an exceptional scenario, as the detector takes the opportunity from any other detector to determine the file type.
Example detector array which can be extended and provided to each public method via the fileTypeOptions argument:
import {FileTypeParser} from 'file-type';
const customDetectors = [
async tokenizer => {
const unicornHeader = [85, 78, 73, 67, 79, 82, 78]; // 'UNICORN' as decimal string
const buffer = Buffer.alloc(7);
await tokenizer.peekBuffer(buffer, {length: unicornHeader.length, mayBeLess: true});
if (unicornHeader.every((value, index) => value === buffer[index])) {
return {ext: 'unicorn', mime: 'application/unicorn'};
}
return undefined;
},
];
const buffer = Buffer.from('UNICORN');
const parser = new FileTypeParser({customDetectors});
const fileType = await parser.fromBuffer(buffer);
console.log(fileType);3g2- Multimedia container format defined by the 3GPP2 for 3G CDMA2000 multimedia services3gp- Multimedia container format defined by the Third Generation Partnership Project (3GPP) for 3G UMTS multimedia services3mf- 3D Manufacturing Format7z- 7-Zip archiveZ- Unix Compressed Fileaac- Advanced Audio Codingac3- ATSC A/52 Audio Fileace- ACE archiveai- Adobe Illustrator Artworkaif- Audio Interchange filealias- macOS Alias fileamr- Adaptive Multi-Rate audio codecape- Monkey's Audioapng- Animated Portable Network Graphicsar- Archive filearj- Archive filearrow- Columnar format for tables of dataarw- Sony Alpha Raw image fileasar- Archive format primarily used to enclose Electron applicationsasf- Advanced Systems Formatavi- Audio Video Interleave fileavif- AV1 Image File Formatavro- Object container file developed by Apache Avroblend- Blender projectbmp- Bitmap image filebpg- Better Portable Graphics filebz2- Archive filecab- Cabinet filecfb- Compound File Binary Formatchm- Microsoft Compiled HTML Helpclass- Java class filecpio- Cpio archivecr2- Canon Raw image file (v2)cr3- Canon Raw image file (v3)crx- Google Chrome extensioncur- Icon filedcm- DICOM Image Filedeb- Debian packagedmg- Apple Disk Imagedng- Adobe Digital Negative image filedocx- Microsoft Word documentdsf- Sony DSD Stream File (DSF)dwg- Autodesk CAD fileelf- Unix Executable and Linkable Formateot- Embedded OpenType fonteps- Encapsulated PostScriptepub- E-book fileexe- Executable filef4a- Audio-only ISO base media file format used by Adobe Flash Playerf4b- Audiobook and podcast ISO base media file format used by Adobe Flash Playerf4p- ISO base media file format protected by Adobe Access DRM used by Adobe Flash Playerf4v- ISO base media file format used by Adobe Flash Playerfbx- Filmbox is a proprietary file format used to provide interoperability between digital content creation apps.flac- Free Lossless Audio Codecflif- Free Lossless Image Formatflv- Flash videogif- Graphics Interchange Formatglb- GL Transmission Formatgz- Archive fileheic- High Efficiency Image File Formaticc- ICC Profileicns- Apple Icon imageico- Windows icon fileics- iCalendarindd- Adobe InDesign documentit- Audio module format: Impulse Trackerj2c- JPEG 2000jls- Lossless/near-lossless compression standard for continuous-tone imagesjp2- JPEG 2000jpg- Joint Photographic Experts Group imagejpm- JPEG 2000jpx- JPEG 2000jxl- JPEG XL image formatjxr- Joint Photographic Experts Group extended rangektx- OpenGL and OpenGL ES textureslnk- Microsoft Windows file shortcutlz- Archive filelzh- LZH archivem4a- Audio-only MPEG-4 filesm4b- Audiobook and podcast MPEG-4 files, which also contain metadata including chapter markers, images, and hyperlinksm4p- MPEG-4 files with audio streams encrypted by FairPlay Digital Rights Management as were sold through the iTunes Storem4v- Video container format developed by Apple, which is very similar to the MP4 formatmacho- Mach-O binary formatmid- Musical Instrument Digital Interface filemie- Dedicated meta information format which supports storage of binary as well as textual meta informationmj2- Motion JPEG 2000mkv- Matroska video filemobi- Mobipocketmov- QuickTime video filemp1- MPEG-1 Audio Layer Imp2- MPEG-1 Audio Layer IImp3- Audio filemp4- MPEG-4 Part 14 video filempc- Musepack (SV7 & SV8)mpg- MPEG-1 filemts- MPEG-2 Transport Stream, both raw and Blu-ray Disc Audio-Video (BDAV) versionsmxf- Material Exchange Formatnef- Nikon Electronic Format image filenes- Nintendo NES ROModp- OpenDocument for presentationsods- OpenDocument for spreadsheetsodt- OpenDocument for word processingoga- Audio fileogg- Audio fileogm- Audio fileogv- Audio fileogx- Audio fileopus- Audio fileorf- Olympus Raw image fileotf- OpenType fontparquet- Apache Parquetpcap- Libpcap File Formatpdf- Portable Document Formatpgp- Pretty Good Privacypng- Portable Network Graphicspptx- Microsoft Powerpoint documentps- Postscriptpsd- Adobe Photoshop documentpst- Personal Storage Table fileqcp- Tagged and chunked dataraf- Fujifilm RAW image filerar- Archive filerpm- Red Hat Package Manager filertf- Rich Text Formatrw2- Panasonic RAW image files3m- Audio module format: ScreamTracker 3shp- Geospatial vector data formatskp- SketchUpspx- Audio filesqlite- SQLite filestl- Standard Tesselated Geometry File Format (ASCII only)swf- Adobe Flash Player filetar- Tarball archive filetif- Tagged Image filettf- TrueType fontvcf- vCardvoc- Creative Voice Filewasm- WebAssembly intermediate compiled formatwav- Waveform Audio filewebm- Web video filewebp- Web Picture formatwoff- Web Open Font Formatwoff2- Web Open Font Formatwv- WavPackxcf- eXperimental Computing Facilityxlsx- Microsoft Excel documentxm- Audio module format: FastTracker 2xml- eXtensible Markup Languagexpi- XPInstall filexz- Compressed filezip- Archive filezst- Archive file
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 outis-svgfor something that mostly works.
Type: ITokenizer
Usable as source of the examined file.
Type: FileTypeResult
An object having an ext (extension) and mime (mime type) property.
Detected by the standard detections or a previous custom detection. Undefined if no matching fileTypeResult could be found.
- file-type-cli - CLI for this module
- image-dimensions - Get the dimensions of an image