For the creation of RFC4122 UUIDs

• Complete - Support for RFC4122 version 1, 3, 4, and 5 UUIDs
• Cross-platform - Support for ...
  • CommonJS, ECMAScript Modules and CDN builds
  • NodeJS 12+ (LTS releases)
  • Chrome, Safari, Firefox, Edge browsers
  • Webpack and rollup.js module bundlers
  • React Native / Expo
• Secure - Cryptographically-strong random values
• Small - Zero-dependency, small footprint, plays nice with "tree shaking" packagers
• CLI - Includes the uuid command line utility

Note Upgrading from uuid@3? Your code is probably okay, but check out Upgrading From uuid@3 for details.

Note Only interested in creating a version 4 UUID? You might be able to use crypto.randomUUID(), eliminating the need to install this library.

To create a random UUID...

1. Install

npm install uuid

2. Create a UUID (ES6 module syntax)

import { v4 as uuidv4 } from 'uuid';
uuidv4(); // ⇨ '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d'

... or using CommonJS syntax:

const { v4: uuidv4 } = require('uuid');
uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'

For timestamp UUIDs, namespace UUIDs, and other options read on ...

The nil UUID string (all zeros).

Example:

import { NIL as NIL_UUID } from 'uuid';

NIL_UUID; // ⇨ '00000000-0000-0000-0000-000000000000'

Convert UUID string to array of bytes

Note: Ordering of values in the byte arrays used by parse() and stringify() follows the left ↠ right order of hex-pairs in UUID strings. As shown in the example below.

Example:

import { parse as uuidParse } from 'uuid';

// Parse a UUID
const bytes = uuidParse('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b');

// Convert to hex strings to show byte order (for documentation purposes)
[...bytes].map((v) => v.toString(16).padStart(2, '0')); // ⇨ 
  // [
  //   '6e', 'c0', 'bd', '7f',
  //   '11', 'c0', '43', 'da',
  //   '97', '5e', '2a', '8a',
  //   'd9', 'eb', 'ae', '0b'
  // ]

Convert array of bytes to UUID string

Note: Ordering of values in the byte arrays used by parse() and stringify() follows the left ↠ right order of hex-pairs in UUID strings. As shown in the example below.

Example:

import { stringify as uuidStringify } from 'uuid';

const uuidBytes = [
  0x6e, 0xc0, 0xbd, 0x7f, 0x11, 0xc0, 0x43, 0xda, 0x97, 0x5e, 0x2a, 0x8a, 0xd9, 0xeb, 0xae, 0x0b,
];

uuidStringify(uuidBytes); // ⇨ '6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'

Create an RFC version 1 (timestamp) UUID

Note: The default node id (the last 12 digits in the UUID) is generated once, randomly, on process startup, and then remains unchanged for the duration of the process.

Note: options.random and options.rng are only meaningful on the very first call to v1(), where they may be passed to initialize the internal node and clockseq fields.

Example:

import { v1 as uuidv1 } from 'uuid';

uuidv1(); // ⇨ '2c5ea4c0-4067-11e9-8bad-9b1deb4d3b7d'

Example using options:

import { v1 as uuidv1 } from 'uuid';

const v1options = {
  node: [0x01, 0x23, 0x45, 0x67, 0x89, 0xab],
  clockseq: 0x1234,
  msecs: new Date('2011-11-01').getTime(),
  nsecs: 5678,
};
uuidv1(v1options); // ⇨ '710b962e-041c-11e1-9234-0123456789ab'

Create an RFC version 3 (namespace w/ MD5) UUID

API is identical to v5(), but uses "v3" instead.

⚠️ Note: Per the RFC, "If backward compatibility is not an issue, SHA-1 [Version 5] is preferred."

Create an RFC version 4 (random) UUID

Example:

import { v4 as uuidv4 } from 'uuid';

uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'

Example using predefined random values:

import { v4 as uuidv4 } from 'uuid';

const v4options = {
  random: [
    0x10, 0x91, 0x56, 0xbe, 0xc4, 0xfb, 0xc1, 0xea, 0x71, 0xb4, 0xef, 0xe1, 0x67, 0x1c, 0x58, 0x36,
  ],
};
uuidv4(v4options); // ⇨ '109156be-c4fb-41ea-b1b4-efe1671c5836'

Create an RFC version 5 (namespace w/ SHA-1) UUID

Note: The RFC DNS and URL namespaces are available as v5.DNS and v5.URL.

Example with custom namespace:

import { v5 as uuidv5 } from 'uuid';

// Define a custom namespace.  Readers, create your own using something like
// https://www.uuidgenerator.net/
const MY_NAMESPACE = '1b671a64-40d5-491e-99b0-da01ff1f3341';

uuidv5('Hello, World!', MY_NAMESPACE); // ⇨ '630eb68f-e0fa-5ecc-887a-7c7a62614681'

Example with RFC URL namespace:

import { v5 as uuidv5 } from 'uuid';

uuidv5('https://www.w3.org/', uuidv5.URL); // ⇨ 'c106a26a-21bb-5538-8bf2-57095d1976c1'

Test a string to see if it is a valid UUID

Example:

import { validate as uuidValidate } from 'uuid';

uuidValidate('not a UUID'); // ⇨ false
uuidValidate('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'); // ⇨ true

Using validate and version together it is possible to do per-version validation, e.g. validate for only v4 UUIds.

import { version as uuidVersion } from 'uuid';
import { validate as uuidValidate } from 'uuid';

function uuidValidateV4(uuid) {
  return uuidValidate(uuid) && uuidVersion(uuid) === 4;
}

const v1Uuid = 'd9428888-122b-11e1-b85c-61cd3cbb3210';
const v4Uuid = '109156be-c4fb-41ea-b1b4-efe1671c5836';

uuidValidateV4(v4Uuid); // ⇨ true
uuidValidateV4(v1Uuid); // ⇨ false

Detect RFC version of a UUID

Example:

import { version as uuidVersion } from 'uuid';

uuidVersion('45637ec4-c85f-11ea-87d0-0242ac130003'); // ⇨ 1
uuidVersion('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'); // ⇨ 4

UUIDs can be generated from the command line using uuid.

$ npx uuid
ddeb27fb-d9a0-4624-be4d-4615062daed4

The default is to generate version 4 UUIDS, however the other versions are supported. Type uuid --help for details:

$ npx uuid --help

Usage:
  uuid
  uuid v1
  uuid v3 <name> <namespace uuid>
  uuid v4
  uuid v5 <name> <namespace uuid>
  uuid --help

Note: <namespace uuid> may be "URL" or "DNS" to use the corresponding UUIDs
defined by RFC4122

This library comes with ECMAScript Modules (ESM) support for Node.js versions that support it (example) as well as bundlers like rollup.js (example) and webpack (example) (targeting both, Node.js and browser environments).

import { v4 as uuidv4 } from 'uuid';
uuidv4(); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'

To run the examples you must first create a dist build of this library in the module root:

npm run build

To load this module directly into modern browsers that support loading ECMAScript Modules you can make use of jspm:

<script type="module">
  import { v4 as uuidv4 } from 'https://jspm.dev/uuid';
  console.log(uuidv4()); // ⇨ '1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed'
</script>

As of uuid@9 UMD (Universal Module Definition) builds are no longer shipped with this library.

If you need a UMD build of this library, use a bundler like Webpack or Rollup. Alternatively, refer to the documentation of [email protected] which was the last version that shipped UMD builds.

This module may generate duplicate UUIDs when run in clients with deterministic random number generators, such as Googlebot crawlers. This can cause problems for apps that expect client-generated UUIDs to always be unique. Developers should be prepared for this and have a strategy for dealing with possible collisions, such as:

• Check for duplicate UUIDs, fail gracefully
• Disable write operations for Googlebot clients

This error occurs in environments where the standard crypto.getRandomValues() API is not supported. This issue can be resolved by adding an appropriate polyfill:

1. Install react-native-get-random-values
2. Import it before uuid. Since uuid might also appear as a transitive dependency of some other imports it's safest to just import react-native-get-random-values as the very first thing in your entry point:

import 'react-native-get-random-values';
import { v4 as uuidv4 } from 'uuid';

Note: If you are using Expo, you must be using at least [email protected] and [email protected].

In Edge <= 18, Web Crypto is not supported in Web Workers or Service Workers and we are not aware of a polyfill (let us know if you find one, please).

Support for IE11 and other legacy browsers has been dropped as of uuid@9. If you need to support legacy browsers, you can always transpile the uuid module source yourself (e.g. using Babel).

uuid@7 did not come with native ECMAScript Module (ESM) support for Node.js. Importing it in Node.js ESM consequently imported the CommonJS source with a default export. This library now comes with true Node.js ESM support and only provides named exports.

Instead of doing:

import uuid from 'uuid';
uuid.v4();

you will now have to use the named exports:

import { v4 as uuidv4 } from 'uuid';
uuidv4();

Deep requires like require('uuid/v4') which have been deprecated in uuid@7 are no longer supported.

"Wait... what happened to uuid@4 thru uuid@6?!?"

In order to avoid confusion with RFC version 4 and version 5 UUIDs, and a possible version 6, releases 4 thru 6 of this module have been skipped.

uuid@3 encouraged the use of deep requires to minimize the bundle size of browser builds:

const uuidv4 = require('uuid/v4'); // <== NOW DEPRECATED!
uuidv4();

As of uuid@7 this library now provides ECMAScript modules builds, which allow packagers like Webpack and Rollup to do "tree-shaking" to remove dead code. Instead, use the import syntax:

import { v4 as uuidv4 } from 'uuid';
uuidv4();

... or for CommonJS:

const { v4: uuidv4 } = require('uuid');
uuidv4();

uuid@3 was exporting the Version 4 UUID method as a default export:

const uuid = require('uuid'); // <== REMOVED!

This usage pattern was already discouraged in uuid@3 and has been removed in uuid@7.

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