A comprehensive library for mime-type mapping

2.4.4  •  Published 5 months ago  •  by Robert Kieffer  •  MIT License


A comprehensive, compact MIME type module.

Build Status

Version 2 Notes

Version 2 is a breaking change from 1.x as the semver implies. Specifically:

  • lookup() renamed to getType()
  • extension() renamed to getExtension()
  • charset() and load() methods have been removed

If you prefer the legacy version of this module please npm install mime@^1. Version 1 docs may be found here.



npm install mime


It is recommended that you use a bundler such as webpack or browserify to package your code. However, browser-ready versions are available via wzrd.in. E.g. For the full version:

<script src="https://wzrd.in/standalone/mime@latest"></script>
mime.getType(...); // etc.

Or, for the mime/lite version:

<script src="https://wzrd.in/standalone/mime%2flite@latest"></script>
mimelite.getType(...); // (Note `mimelite` here)

Quick Start

For the full version (800+ MIME types, 1,000+ extensions):

const mime = require('mime');

mime.getType('txt');                    // ⇨ 'text/plain'
mime.getExtension('text/plain');        // ⇨ 'txt'

See Mime API below for API details.

Lite Version

There is also a “lite” version of this module that omits vendor-specific (*/vnd.*) and experimental (*/x-*) types. It weighs in at ~2.5KB, compared to 8KB for the full version. To load the lite version:

const mime = require('mime/lite');

Mime .vs. mime-types .vs. mime-db modules

For those of you wondering about the difference between these [popular] NPM modules, here’s a brief rundown …

mime-db is “the source of truth” for MIME type information. It is not an API. Rather, it is a canonical dataset of mime type definitions pulled from IANA, Apache, NGINX, and custom mappings submitted by the Node.js community.

mime-types is a thin wrapper around mime-db that provides an API drop-in compatible(ish) with mime @ < v1.3.6 API.

mime is, as of v2, a self-contained module bundled with a pre-optimized version of the mime-db dataset. It provides a simplified API with the following characteristics:

  • Intelligently resolved type conflicts (See mime-score for details)
  • Method naming consistent with industry best-practices
  • Compact footprint. E.g. The minified+compressed sizes of the various modules:
Module Size
mime-db 18 KB
mime-types same as mime-db
mime 8 KB
mime/lite 2 KB

Mime API

Both require('mime') and require('mime/lite') return instances of the MIME class, documented below.

Note: Inputs to this API are case-insensitive. Outputs (returned values) will be lowercase.

new Mime(typeMap, … more maps)

Most users of this module will not need to create Mime instances directly. However if you would like to create custom mappings, you may do so as follows …

// Require Mime class
const Mime = require('mime/Mime');

// Define mime type -> extensions map
const typeMap = {
  'text/abc': ['abc', 'alpha', 'bet'],
  'text/def': ['leppard']

// Create and use Mime instance
const myMime = new Mime(typeMap);
myMime.getType('abc');            // ⇨ 'text/abc'
myMime.getExtension('text/def');  // ⇨ 'leppard'

If more than one map argument is provided, each map is define()ed (see below), in order.


Get mime type for the given path or extension. E.g.

mime.getType('js');             // ⇨ 'application/javascript'
mime.getType('json');           // ⇨ 'application/json'

mime.getType('txt');            // ⇨ 'text/plain'
mime.getType('dir/text.txt');   // ⇨ 'text/plain'
mime.getType('dir\\text.txt');  // ⇨ 'text/plain'
mime.getType('.text.txt');      // ⇨ 'text/plain'
mime.getType('.txt');           // ⇨ 'text/plain'

null is returned in cases where an extension is not detected or recognized

mime.getType('foo/txt');        // ⇨ null
mime.getType('bogus_type');     // ⇨ null


Get extension for the given mime type. Charset options (often included in Content-Type headers) are ignored.

mime.getExtension('text/plain');               // ⇨ 'txt'
mime.getExtension('application/json');         // ⇨ 'json'
mime.getExtension('text/html; charset=utf8');  // ⇨ 'html'

mime.define(typeMap[, force = false])

Define [more] type mappings.

typeMap is a map of type -> extensions, as documented in new Mime, above.

By default this method will throw an error if you try to map a type to an extension that is already assigned to another type. Passing true for the force argument will suppress this behavior (overriding any previous mapping).

mime.define({'text/x-abc': ['abc', 'abcd']});

mime.getType('abcd');            // ⇨ 'text/x-abc'
mime.getExtension('text/x-abc')  // ⇨ 'abc'

Command Line

mime [path_or_extension]


> mime scripts/jquery.js

Markdown generated from src/README_js.md by RunMD Logo


Weekly Downloads



Last ver 5 months ago
Created 9 years ago
Last commit 3 months ago
13 days between commits


Node version: 8.15.1
74.9K unpacked


MIT License
OSI Approved
0 vulnerabilities


48 contributors
Robert Kieffer
Maintainer, 193 commits, 54 merges, 11 PRs
Benjamin Thomas
25 commits
Nick Baugh
4 commits, 2 PRs
Nathan Rajlich
3 commits, 1 PRs
Works at zeit
Joshua Holbrook
3 commits, 1 PRs
Works at Squarespace
Ionică Bizău
3 commits, 1 PRs
Works at Bloggify cdnjs nodejs


Ready for the next level?
Join Devstore's founding team to help us build the ultimate open-source app store, work with the latest technologies, and enjoy great culture, impact and autonomy
© 2019 Devstore, Inc.
Devstore helps developers find and use open-source packages, so they can focus on building amazing things