https://github.com/ulid/javascript
Universally Unique Lexicographically Sortable Identifier
https://github.com/ulid/javascript
javascript ulid uuid
Last synced: 8 days ago
JSON representation
Universally Unique Lexicographically Sortable Identifier
- Host: GitHub
- URL: https://github.com/ulid/javascript
- Owner: ulid
- License: mit
- Created: 2016-06-13T16:14:51.000Z (almost 9 years ago)
- Default Branch: master
- Last Pushed: 2025-03-24T20:28:17.000Z (about 1 month ago)
- Last Synced: 2025-04-24T08:10:29.721Z (9 days ago)
- Topics: javascript, ulid, uuid
- Language: TypeScript
- Homepage:
- Size: 269 KB
- Stars: 3,153
- Watchers: 20
- Forks: 109
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-nodejs - ulid - Universally Unique Lexicographically Sortable Identifier.  (Repository / Text/String)
- awesome-repositories - ulid/javascript - Universally Unique Lexicographically Sortable Identifier (JavaScript)
README
# Universally Unique Lexicographically Sortable Identifier
[](https://github.com/ulid/javascript/actions/workflows/test.yml)
[](https://codecov.io/gh/ulid/javascript)
[](https://www.npmjs.com/package/ulid) [](https://www.npmjs.com/package/ulid)
ULIDs are unique, sortable identifiers that work much in the same way as UUIDs, though with some improvements:
* Lexicographically sortable
* Canonically encoded as a 26 character string, as opposed to the 36 character UUID
* Uses Crockford's base32 for better efficiency and readability (5 bits per character)
* Monotonic sort order (correctly detects and handles the same millisecond)
ULIDs also provide:
* 128-bit compatibility with UUID
* 1.21e+24 unique IDs per millisecond
* Case insensitivity
* No special characters (URL safe)
UUID can be suboptimal for many uses-cases because:
- It isn't the most character efficient way of encoding 128 bits of randomness
- UUID v1/v2 is impractical in many environments, as it requires access to a unique, stable MAC address
- UUID v3/v5 requires a unique seed and produces randomly distributed IDs, which can cause fragmentation in many data structures
- UUID v4 provides no other information than randomness which can cause fragmentation in many data structures
## Installation
Install using NPM:
```shell
npm install ulid --save
```
### Compatibility
ULID supports the following environments:
| Version | NodeJS | Browsers | React-Native | Web Workers | Edge Functions |
|-----------|-----------|---------------|---------------|---------------|-------------------|
| v3 | v18+ | Yes | Yes | Yes | ? |
| v2 | v16+ | Yes | No | No | No |
Additionally, both ESM and CommonJS entrypoints are provided.
## Usage
To quickly generate a ULID, you can simply import the `ulid` function:
```typescript
import { ulid } from "ulid";
ulid(); // "01ARZ3NDEKTSV4RRFFQ69G5FAV"
```
### Seed Time
You can also input a seed time which will consistently give you the same string for the time component. This is useful for migrating to ulid.
```typescript
ulid(1469918176385) // "01ARYZ6S41TSV4RRFFQ69G5FAV"
```
### Monotonic ULIDs
To generate monotonically increasing ULIDs, create a monotonic counter with `monotonicFactory`.
> Note that the same seed time is being passed in for this example to demonstrate its behaviour when generating multiple ULIDs within the same millisecond
```typescript
import { monotonicFactory } from "ulid";
const ulid = monotonicFactory();
// Strict ordering for the same timestamp, by incrementing the least-significant random bit by 1
ulid(150000); // "000XAL6S41ACTAV9WEVGEMMVR8"
ulid(150000); // "000XAL6S41ACTAV9WEVGEMMVR9"
ulid(150000); // "000XAL6S41ACTAV9WEVGEMMVRA"
ulid(150000); // "000XAL6S41ACTAV9WEVGEMMVRB"
ulid(150000); // "000XAL6S41ACTAV9WEVGEMMVRC"
// Even if a lower timestamp is passed (or generated), it will preserve sort order
ulid(100000); // "000XAL6S41ACTAV9WEVGEMMVRD"
```
### Pseudo-Random Number Generators
`ulid` automatically detects a suitable (cryptographically-secure) PRNG. In the browser it will use `crypto.getRandomValues` and on NodeJS it will use `crypto.randomBytes`.
#### Using `Math.random` (insecure)
By default, `ulid` will not use `Math.random` to generate random values. You can bypass this limitation by overriding the PRNG:
```typescript
const ulid = monotonicFactory(() => Math.random());
ulid(); // "01BXAVRG61YJ5YSBRM51702F6M"
```
### Validity
You can verify if a value is a valid ULID by using `isValid`:
```typescript
import { isValid } from "ulid";
isValid("01ARYZ6S41TSV4RRFFQ69G5FAV"); // true
isValid("01ARYZ6S41TSV4RRFFQ69G5FA"); // false
```
### ULID Time
You can encode and decode ULID timestamps by using `encodeTime` and `decodeTime` respectively:
```typescript
import { decodeTime } from "ulid";
decodeTime("01ARYZ6S41TSV4RRFFQ69G5FAV"); // 1469918176385
```
Note that while `decodeTime` works on full ULIDs, `encodeTime` encodes only the _time portion_ of ULIDs:
```typescript
import { encodeTime } from "ulid";
encodeTime(1469918176385); // "01ARYZ6S41"
```
### Tests
Install dependencies using `npm install` first, and then simply run `npm test` to run the test suite.
### CLI
`ulid` can be used on the command line, either via global install:
```shell
npm install -g ulid
ulid
```
Or via `npx`:
```shell
npx ulid
```
You can also generate multiple IDs at the same time:
```shell
ulid --count 15
```
## Specification
You can find the full specification, as well as information regarding implementations in other languages, over at [ulid/spec](https://github.com/ulid/spec).
## Performance
You can test `ulid`'s performance by running `npm run bench`:
```
Simple ulid x 56,782 ops/sec ±2.50% (86 runs sampled)
ulid with timestamp x 58,574 ops/sec ±1.80% (87 runs sampled)
Done!
```