# uuid [](https://github.com/uuidjs/uuid/actions?query=workflow%3ACI) [](https://github.com/uuidjs/uuid/actions/workflows/browser.yml)
For the creation of [RFC9562](https://www.rfc-editor.org/rfc/rfc9562.html) (formerly [RFC4122](https://www.rfc-editor.org/rfc/rfc4122.html)) UUIDs
- **Complete** - Support for all RFC9562 UUID versions
- **Cross-platform** - Support for...
- [Typescript](#support)
- [Chrome, Safari, Firefox, and Edge](#support)
- [NodeJS](#support)
- [React Native / Expo](#react-native--expo)
- **Secure** - Uses modern `crypto` API for random values
- **Compact** - Zero-dependency, [tree-shakable](https://developer.mozilla.org/en-US/docs/Glossary/Tree_shaking)
- **CLI** - [`uuid` command line](#command-line) utility
> [!NOTE]
>
> Starting with `uuid@12` CommonJS is no longer supported. See [implications](https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c) and [motivation](https://github.com/uuidjs/uuid/issues/881) for details.
## Quickstart
**1. Install**
```shell
npm install uuid
```
**2. Create a UUID**
```javascript
import { v4 as uuidv4 } from "uuid";
uuidv4(); // ⇨ 'ab16e731-6cee-424d-81a0-5929e9bdb0cc'
```
For timestamp UUIDs, namespace UUIDs, and other options read on ...
## API Summary
| [`uuid.NIL`](#uuidnil) | The nil UUID string (all zeros) | New in `uuid@8.3` |
| [`uuid.MAX`](#uuidmax) | The max UUID string (all ones) | New in `uuid@9.1` |
| [`uuid.parse()`](#uuidparsestr) | Convert UUID string to array of bytes | New in `uuid@8.3` |
| [`uuid.stringify()`](#uuidstringifyarr-offset) | Convert array of bytes to UUID string | New in `uuid@8.3` |
| [`uuid.v1()`](#uuidv1options-buffer-offset) | Create a version 1 (timestamp) UUID | |
| [`uuid.v1ToV6()`](#uuidv1tov6uuid) | Create a version 6 UUID from a version 1 UUID | New in `uuid@10` |
| [`uuid.v3()`](#uuidv3name-namespace-buffer-offset) | Create a version 3 (namespace w/ MD5) UUID | |
| [`uuid.v4()`](#uuidv4options-buffer-offset) | Create a version 4 (random) UUID | |
| [`uuid.v5()`](#uuidv5name-namespace-buffer-offset) | Create a version 5 (namespace w/ SHA-1) UUID | |
| [`uuid.v6()`](#uuidv6options-buffer-offset) | Create a version 6 (timestamp, reordered) UUID | New in `uuid@10` |
| [`uuid.v6ToV1()`](#uuidv6tov1uuid) | Create a version 1 UUID from a version 6 UUID | New in `uuid@10` |
| [`uuid.v7()`](#uuidv7options-buffer-offset) | Create a version 7 (Unix Epoch time-based) UUID | New in `uuid@10` |
| ~~[`uuid.v8()`](#uuidv8)~~ | "Intentionally left blank" | |
| [`uuid.validate()`](#uuidvalidatestr) | Test a string to see if it is a valid UUID | New in `uuid@8.3` |
| [`uuid.version()`](#uuidversionstr) | Detect RFC version of a UUID | New in `uuid@8.3` |
## API
### uuid.NIL
The nil UUID string (all zeros).
Example:
```javascript
import { NIL as NIL_UUID } from "uuid";
NIL_UUID; // ⇨ '00000000-0000-0000-0000-000000000000'
```
### uuid.MAX
The max UUID string (all ones).
Example:
```javascript
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:
```javascript
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:
```javascript
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 = (random)` ] | RFC "node" field as an `Array[6]` of byte values (per 4.1.6) |
| [`options.clockseq = (random)`] | RFC "clock sequence" as a `Number` between 0 - 0x3fff |
| [`options.msecs = (current time)`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch) |
| [`options.nsecs = 0`] | RFC "timestamp" field (`Number` of nanoseconds to add to `msecs`, should be 0-10,000) |
| [`options.random = (random)`] | `Array` of 16 random bytes (0-255) used to generate other fields, above |
| [`options.rng`] | Alternative to `options.random`, a `Function` that returns an `Array` of 16 random bytes (0-255) |
| [`buffer`] | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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 |
Example:
```javascript
import { v1 as uuidv1 } from "uuid";
uuidv1(); // ⇨ '4d9d2960-31d0-11f1-aba8-29728d41eeed'
```
Example using `options`:
```javascript
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
```javascript
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`] | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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:
```javascript
import { v4 as uuidv4 } from "uuid";
uuidv4(); // ⇨ '7934256a-bc92-4b69-b240-f9e463881aea'
```
Example using predefined `random` values:
```javascript
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`] | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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:
```javascript
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:
```javascript
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().
```javascript
import { v6 as uuidv6 } from "uuid";
uuidv6(); // ⇨ '1f131d04-d9dc-65a0-9516-5be66631ce97'
```
Example using `options`:
```javascript
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
```javascript
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 = (current time)`] | RFC "timestamp" field (`Number` of milliseconds, unix epoch) |
| [`options.random = (random)`] | `Array` of 16 random bytes (0-255) used to generate other fields, above |
| [`options.rng`] | Alternative to `options.random`, a `Function` that returns an `Array` of 16 random bytes (0-255) |
| [`options.seq = (random)`] | 32-bit sequence `Number` between 0 - 0xffffffff. This may be provided to help ensure uniqueness for UUIDs generated within the same millisecond time interval. Default = random value. |
| [`buffer`] | `Uint8Array` or `Uint8Array` subtype (e.g. Node.js `Buffer`). If provided, binary UUID is written into the array, 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:
```javascript
import { v7 as uuidv7 } from "uuid";
uuidv7(); // ⇨ '019d637c-c6fb-74e9-8b9d-2f1d459a4201'
```
### ~~uuid.v8()~~
**_"Intentionally left blank"_**
> [!NOTE]
> Version 8 (experimental) UUIDs are "[for experimental or vendor-specific use cases](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-8)". 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:
```javascript
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.
```javascript
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:
```javascript
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`.
```shell
$ 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:
```shell
$ 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
Prior to `uuid@11`, it was possible for `options` state to interfere with the internal state used to ensure uniqueness of timestamp-based UUIDs (the `v1()`, `v6()`, and `v7()` methods). Starting with `uuid@11`, this issue has been addressed by using the presence of the `options` argument as a flag to select between two possible behaviors:
- Without `options`: Internal state is utilized to improve UUID uniqueness.
- With `options`: Internal state is **NOT** used and, instead, appropriate defaults are applied as needed.
## Support
**Browsers**: `uuid` [builds are tested](/uuidjs/uuid/blob/main/wdio.conf.js) against the latest version of desktop Chrome, Safari, Firefox, and Edge. Mobile versions of these same browsers are expected to work but aren't currently tested.
**Node**: `uuid` [builds are tested](https://github.com/uuidjs/uuid/blob/main/.github/workflows/ci.yml#L26-L27) against node ([LTS releases](https://github.com/nodejs/Release)), plus one prior. E.g. At the time of this writing `node@20` is the "maintenance" release and `node@24` is the "current" release, so `uuid` supports `node@20`-`node@24`.
**Typescript**: TS versions released within the past two years are supported. [source](https://github.com/microsoft/TypeScript/issues/49088#issuecomment-2468723715)
## Known issues
### "getRandomValues() not supported"
This error occurs in environments where the standard [`crypto.getRandomValues()`](https://developer.mozilla.org/en-US/docs/Web/API/Crypto/getRandomValues) API is not supported. This issue can be resolved by adding an appropriate polyfill:
#### React Native / Expo
1. Install [`react-native-get-random-values`](https://github.com/LinusU/react-native-get-random-values#readme)
1. 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:
```javascript
import "react-native-get-random-values";
import { v4 as uuidv4 } from "uuid";
```
---
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