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For the creation of RFC9562 (formally RFC4122) UUIDs

  • Complete - Support for all RFC9562 UUID versions
  • Cross-platform - Support for ...
  • Secure - Cryptographically-strong random values
  • Compact - No dependencies, tree-shakable
  • CLI - Includes the uuid command line utility
  • Typescript - Types now included

Note

uuid@11 has the following breaking changes:

  • Passing options to v1(), v6(), and v7() now behaves slightly differently. See details
  • Binary UUIDs are now of type Uint8Array. This may affect code utilizing parse(), stringify(), or that passes a buf argument to any of the v1()-v7() methods.

Quickstart

1. Install

npm install uuid

2. Create a UUID

ESM-syntax (must use named exports):

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

... CommonJS:

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

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

API Summary

uuid.NIL The nil UUID string (all zeros) New in uuid@8.3
uuid.MAX The max UUID string (all ones) New in uuid@9.1
uuid.parse() Convert UUID string to array of bytes New in uuid@8.3
uuid.stringify() Convert array of bytes to UUID string New in uuid@8.3
uuid.v1() Create a version 1 (timestamp) UUID
uuid.v1ToV6() Create a version 6 UUID from a version 1 UUID New in uuid@10
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.v6() Create a version 6 (timestamp, reordered) UUID New in uuid@10
uuid.v6ToV1() Create a version 1 UUID from a version 6 UUID New in uuid@10
uuid.v7() Create a version 7 (Unix Epoch time-based) UUID New in uuid@10
uuid.v8() "Intentionally left blank"
uuid.validate() Test a string to see if it is a valid UUID New in uuid@8.3
uuid.version() Detect RFC version of a UUID New in uuid@8.3

API

uuid.NIL

The nil UUID string (all zeros).

Example:

import { NIL as NIL_UUID } from 'uuid';

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

uuid.MAX

The max UUID string (all ones).

Example:

import { MAX as MAX_UUID } from 'uuid';

MAX_UUID; // ⇨ 'ffffffff-ffff-ffff-ffff-ffffffffffff'

uuid.parse(str)

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
uuidParse('6ec0bd7f-11c0-43da-975e-2a8ad9ebae0b'); // ⇨ 
  // Uint8Array(16) [
  //   110, 192, 189, 127,  17,
  //   192,  67, 218, 151,  94,
  //    42, 138, 217, 235, 174,
  //    11
  // ]

uuid.stringify(arr[, offset])

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 = Uint8Array.of(
  0x6e, 0xc0, 0xbd, 0x7f,
  0x11, 0xc0, 0x43, 0xda,
  0x97, 0x5e, 0x2a, 0x8a,
  0xd9, 0xeb, 0xae, 0x0b,
);

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

uuid.v1([options[, buffer[, offset]]])

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(); // ⇨ '2c5ea4c0-4067-11e9-9bdd-2b0d7b3dcb6d'

Example using options:

import { v1 as uuidv1 } from 'uuid';

const options = {
  node: Uint8Array.of(0x01, 0x23, 0x45, 0x67, 0x89, 0xab),
  clockseq: 0x1234,
  msecs: new Date('2011-11-01').getTime(),
  nsecs: 5678,
};
uuidv1(options); // ⇨ '710b962e-041c-11e1-9234-0123456789ab'

uuid.v1ToV6(uuid)

Convert a UUID from version 1 to version 6

import { v1ToV6 } from 'uuid';

v1ToV6('92f62d9e-22c4-11ef-97e9-325096b39f47'); // ⇨ '1ef22c49-2f62-6d9e-97e9-325096b39f47'

uuid.v3(name, namespace[, buffer[, offset]])

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

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

Important

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

uuid.v4([options[, buffer[, offset]]])

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(); // ⇨ '9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d'

Example using predefined random values:

import { v4 as uuidv4 } from 'uuid';

const v4options = {
  random: Uint8Array.of(
    0x10, 0x91, 0x56, 0xbe,
    0xc4, 0xfb, 0xc1, 0xea,
    0x71, 0xb4, 0xef, 0xe1,
    0x67, 0x1c, 0x58, 0x36,
  ),
};
uuidv4(v4options); // ⇨ '109156be-c4fb-41ea-b1b4-efe1671c5836'

uuid.v5(name, namespace[, buffer[, offset]])

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'

uuid.v6([options[, buffer[, offset]]])

Create an RFC version 6 (timestamp, reordered) UUID

This method takes the same arguments as uuid.v1().

import { v6 as uuidv6 } from 'uuid';

uuidv6(); // ⇨ '1e940672-c5ea-64c0-9b5d-ab8dfbbd4bed'

Example using options:

import { v6 as uuidv6 } from 'uuid';

const options = {
  node: [0x01, 0x23, 0x45, 0x67, 0x89, 0xab],
  clockseq: 0x1234,
  msecs: new Date('2011-11-01').getTime(),
  nsecs: 5678,
};
uuidv6(options); // ⇨ '1e1041c7-10b9-662e-9234-0123456789ab'

uuid.v6ToV1(uuid)

Convert a UUID from version 6 to version 1

import { v6ToV1 } from 'uuid';

v6ToV1('1ef22c49-2f62-6d9e-97e9-325096b39f47'); // ⇨ '92f62d9e-22c4-11ef-97e9-325096b39f47'

uuid.v7([options[, buffer[, offset]]])

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). Default = Date.now()
[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] 32-bit sequence Number between 0 - 0xffffffff. This may be provided to help insure uniqueness for UUIDs generated within the same millisecond time interval. Default = random value.
[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-705a-b56d-778dfbbd4bed'

uuid.v8()

"Intentionally left blank"

Note

Version 8 (experimental) UUIDs are "for experimental or vendor-specific use cases". The RFC does not define a creation algorithm for them, which is why this package does not offer a v8() method. The validate() and version() methods do work with such UUIDs, however.

uuid.validate(str)

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

uuid.version(str)

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

Note

This method returns 0 for the NIL UUID, and 15 for the MAX UUID.

Command Line

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 RFC9562

options Handling for Timestamp UUIDs

As of uuid@11, all timestamp-based UUID APIs (v1(), v6(), and v7()) now operate in two distinct modes:

  • Without options: If no options argument is passed, these APIs will make use of internal state such as a sequence counter to improve UUID uniqueness.
  • With options: If an options argument of any kind is passed, no internal state is used or updated. Instead, appropriate defaults are used. See the respective APIs for details.

Prior to uuid@11, this distinction was less clear. Internal state was was being combined with options values in ways that were difficult to rationalize about, and that could lead to unpredictable behavior. Hence, this change.


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