Generate UUIDs of versions 1, 3, 4, and 5.

Usage no npm install needed!

<script type="module">
  import uuid1345 from 'https://cdn.skypack.dev/uuid-1345';



Build Status

Generate v1, v3, v4, and v5 UUIDs, strictly conforming to RFC 4122.

npm install --save uuid-1345


  • Actually uses your MAC address for v1 UUIDs
  • Synchronous + Asynchronous API
  • Returns string or Buffer, as you wish
  • Works in NodeJS + io.js (see build status above)
  • Allows you to inspect uuids (check the check function)
  • It's really fast (see here, here, and here)


  • Does not work in the browser due to the use of NodeJS's crypto module.


var UUID = require('uuid-1345');

UUID.v1(function (err, result) {
    console.log("Generated a time-based UUID:\n\t%s\n", result);

UUID.v4(function (err, result) {
    console.log("Generated a random UUID:\n\t%s\n", result);

    namespace: UUID.namespace.url,
    name: "https://github.com/scravy/uuid-1345"
}, function (err, result) {
    console.log("Generated a name-based UUID using MD5:\n\t%s\n", result);

    namespace: UUID.namespace.url,
    name: "https://github.com/scravy/uuid-1345"
}, function (err, result) {
    console.log("Generated a name-based UUID using SHA1:\n\t%s\n", result);

might result in:

Generated a time-based UUID:

Generated a random UUID:
Generated a name-based UUID using MD5:

Generated a name-based UUID using SHA1:

object-oriented UUID interface

var uuid = new UUID('39888f87-fb62-5988-a425-b2ea63f5b81e');
console.log( uuid.version    );
console.log( uuid.variant    );
console.log( uuid.toString() );
console.log( uuid.toBuffer() );
<Buffer 39 88 8f 87 fb 62 59 88 a4 25 b2 ea 63 f5 b8 1e>


UUID.vX([options], [callback]);

where vX is one of v1, v3, v4, or v5.

callback is always optional, you can use the API asynchronously and synchronously.

options that are recognized by every generator are:

encoding: 'ascii' | 'binary' | 'object'

By default the generated UUIDs are ASCII strings.

You can change this to a Buffer object by specifying binary.

Or to a UUID object by specifying object.

UUID.v1([options], [callback])

Generates a time based UUID. Note that you can not generate more than 10000 UUIDs per second. Should this (highly unlikely) scenario happen, the uuid generator will automatically postpone your request until new UUIDs are available.


mac: false | string | Buffer

By default this generator will try to use your mac address (the mac address of your primary network interface). It does so using node-macaddress. If it can not obtain your MAC address it will generate a random value according to RFC 4122 ยง 4.5 and keep that as node id during the lifetime of your process.

The latter behaviour can be enforced by specifying { mac: false }.

It is also possible to provide a custom MAC address: { mac: 'ac:00:00:ac:ff:ff' }.

The MAC address can also be specified as a Buffer of 6 bytes.

clockSeq: integer

The clockSeq is initialized with an arbitrary number. You can specify a custom value for clockSeq.

UUID.v4([options], [callback])

Generates a random version 4 UUID.

This generator is backed by Node's crypto.randomBytes which is moderately slow (slower than Math.random) but has a higher quality (the generated UUIDs are less pseudo-random ;-).


Generated a pseudo-random version 4 UUID. Does not take any options. Does not offer an asynchronous interface.

This generator is backed by Math.random(). It's really fast, but the generated UUIDs are only pseudo-random.

UUID.v3(options, [cb]) / UUID.v5(options, [cb])


Generates a name-based UUID based on a namespace-UUID and an arbitrary name. Both name and namespace are required options.

namespace: uuid as (string | Buffer)

This must be a valid UUID. A few pre-defined namespaces are available in UUID.namespace:

// from rfc4122#appendix-C
UUID.namespace = {
    dns:  "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
    url:  "6ba7b811-9dad-11d1-80b4-00c04fd430c8",
    oid:  "6ba7b812-9dad-11d1-80b4-00c04fd430c8",
    x500: "6ba7b814-9dad-11d1-80b4-00c04fd430c8"

name: string | Buffer

This can be an arbitrary value (including the empty string).

More API

UUID.check(uuid) โ†’ { version: number, variant: string }
UUID.parse(uuid as string) โ†’ uuid as Buffer
UUID.stringify(uuid as Buffer) โ†’ uuid as string