For the creation of RFC4122 UUIDs
- Complete - Support for RFC4122 version 1, 3, 4, 5, and 7 UUIDs
- Cross-platform - Support for ...
- CommonJS, ECMAScript Modules and CDN builds
- Node 12, 14, 16, 18
- 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
Upgrading from uuid@3
? Your code is probably okay, but check out Upgrading From uuid@3
for details.
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 ...
uuid.NIL |
The nil UUID string (all zeros) | New in [email protected] |
uuid.parse() |
Convert UUID string to array of bytes | New in [email protected] |
uuid.stringify() |
Convert array of bytes to UUID string | New in [email protected] |
uuid.v1() |
Create a version 1 (timestamp) UUID | |
uuid.v3() |
Create a version 3 (namespace w/ MD5) UUID | |
uuid.v4() |
Create a version 4 (random) UUID | |
uuid.v5() |
Create a version 5 (namespace w/ SHA-1) UUID | |
uuid.v7() |
Create a version 7 (Unix Epoch time-based) UUID | experimental support |
uuid.validate() |
Test a string to see if it is a valid UUID | New in [email protected] |
uuid.version() |
Detect RFC version of a UUID | New in [email protected] |
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
str |
A valid UUID String |
returns | Uint8Array[16] |
throws | TypeError if str is not a valid UUID |
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
arr |
Array -like collection of 16 values (starting from offset ) between 0-255. |
[offset = 0] |
Number Starting index in the Array |
returns | String |
throws | TypeError if a valid UUID string cannot be generated |
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
[options ] |
Object with one or more of the following properties: |
[options.node ] |
RFC "node" field as an Array[6] of byte values (per 4.1.6) |
[options.clockseq ] |
RFC "clock sequence" as a Number between 0 - 0x3fff |
[options.msecs ] |
RFC "timestamp" field (Number of milliseconds, unix epoch) |
[options.nsecs ] |
RFC "timestamp" field (Number of nanoseconds to add to msecs , should be 0-10,000) |
[options.random ] |
Array of 16 random bytes (0-255) |
[options.rng ] |
Alternative to options.random , a Function that returns an Array of 16 random bytes (0-255) |
[buffer ] |
Array | Buffer If specified, uuid will be written here in byte-form, starting at offset |
[offset = 0] |
Number Index to start writing UUID bytes in buffer |
returns | UUID String if no buffer is specified, otherwise returns buffer |
throws | Error if more than 10M UUIDs/sec are requested |
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.
Create an RFC version 4 (random) UUID
[options ] |
Object with one or more of the following properties: |
[options.random ] |
Array of 16 random bytes (0-255) |
[options.rng ] |
Alternative to options.random , a Function that returns an Array of 16 random bytes (0-255) |
[buffer ] |
Array | Buffer If specified, uuid will be written here in byte-form, starting at offset |
[offset = 0] |
Number Index to start writing UUID bytes in buffer |
returns | UUID String if no buffer is specified, otherwise returns buffer |
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
name |
String | Array |
namespace |
String | Array[16] Namespace UUID |
[buffer ] |
Array | Buffer If specified, uuid will be written here in byte-form, starting at offset |
[offset = 0] |
Number Index to start writing UUID bytes in buffer |
returns | UUID String if no buffer is specified, otherwise returns buffer |
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'
Create an RFC version 7 (random) UUID
[options ] |
Object with one or more of the following properties: |
[options.msecs ] |
RFC "timestamp" field (Number of milliseconds, unix epoch) |
[options.random ] |
Array of 16 random bytes (0-255) |
[options.rng ] |
Alternative to options.random , a Function that returns an Array of 16 random bytes (0-255) |
[options.seq ] |
31 bit monotonic sequence counter as Number between 0 - 0x7fffffff |
[buffer ] |
Array | Buffer If specified, uuid will be written here in byte-form, starting at offset |
[offset = 0] |
Number Index to start writing UUID bytes in buffer |
returns | UUID String if no buffer is specified, otherwise returns buffer |
Example:
import { v7 as uuidv7 } from 'uuid';
uuidv7(); // ⇨ '01695553-c90c-7aad-9bdd-330d7b3dcb6d'
Test a string to see if it is a valid UUID
str |
String to validate |
returns | true if string is a valid UUID, false otherwise |
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
str |
A valid UUID String |
returns | Number The RFC version of the UUID |
throws | TypeError if str is not a valid 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 v7
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:
- Install
react-native-get-random-values
- Import it before
uuid
. Sinceuuid
might also appear as a transitive dependency of some other imports it's safest to just importreact-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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