nanoid README

The project's README from github.com/ai/nanoid. As one markdown file: README.md.

Nano ID

Nano ID logo by Anton Lovchikov

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A tiny, secure, URL-friendly, unique string ID generator for JavaScript.

“An amazing level of senseless perfectionism, which is simply impossible not to respect.”

import { nanoid } from 'nanoid'
model.id = nanoid() //=> "V1StGXR8_Z5jdHi6B-myT"

  Nano ID is built by Evil Martians, an American design and engineering consultancy for developer tools, AI, and cybersecurity startups.

Table of Contents

Comparison with UUID

Nano ID is quite comparable to UUID v4 (random-based). It has a similar number of random bits in the ID (126 in Nano ID and 122 in UUID), so it has a similar collision probability:

For there to be a one in a billion chance of duplication, 103 trillion version 4 IDs must be generated.

There are two main differences between Nano ID and UUID v4:

  1. Nano ID uses a bigger alphabet, so a similar number of random bits are packed in just 21 symbols instead of 36.
  2. Nano ID is faster than crypto.randomUUID and uuid/v4.

Benchmark

$ node ./test/benchmark.js
nope-id                 20,386,830 ops/sec
nanoid                  20,434,827 ops/sec
customAlphabet          20,544,476 ops/sec
crypto.randomUUID       12,865,759 ops/sec
uuid v4                  7,930,104 ops/sec
@napi-rs/uuid            5,573,171 ops/sec
uid/secure               6,308,267 ops/sec
@lukeed/uuid             5,278,597 ops/sec
nanoid for browser         311,497 ops/sec
secure-random-string       301,667 ops/sec
uid-safe.sync              297,815 ops/sec

Non-secure:
uid                     20,286,757 ops/sec
nanoid/non-secure        2,397,594 ops/sec
rndm                     2,445,462 ops/sec

Security

See a good article about random generators theory: Secure random values (in Node.js)

Install

npm install nanoid

JSR

JSR is a replacement for npm with open governance and active development (in contrast to npm).

npx jsr add @sitnik/nanoid

You can use it in Node.js, Deno, Bun, etc.

// Replace `nanoid` to `@sitnik/nanoid` in all imports
import { nanoid } from '@sitnik/nanoid'

For Deno install it by deno add jsr:@sitnik/nanoid or import from jsr:@sitnik/nanoid.

CDN

For quick hacks, you can load Nano ID from CDN. Though, it is not recommended to be used in production because of the lower loading performance.

import { nanoid } from 'https://cdn.jsdelivr.net/npm/nanoid/nanoid.js'

API

By default, Nano ID uses URL-friendly symbols (A-Za-z0-9_-) and returns an ID with 21 characters (to have a collision probability similar to UUID v4).

import { nanoid } from 'nanoid'
model.id = nanoid() //=> "V1StGXR8_Z5jdHi6B-myT"

If you want to reduce the ID size (and increase collisions probability), you can pass the size as an argument.

nanoid(10) //=> "IRFa-VaY2b"

Don’t forget to check the safety of your ID size in our ID collision probability calculator.

You can also use a custom alphabet or a random generator.

Custom Alphabet or Size

customAlphabet returns a function that allows you to create nanoid with your own alphabet and ID size.

import { customAlphabet } from 'nanoid'
const nanoid = customAlphabet('1234567890abcdef', 10)
model.id = nanoid() //=> "4f90d13a42"

import { customAlphabet } from 'nanoid/non-secure'
const nanoid = customAlphabet('1234567890abcdef', 10)
user.id = nanoid()

Check the safety of your custom alphabet and ID size in our ID collision probability calculator. For more alphabets, check out the options in nanoid-dictionary.

Alphabet must contain from 1 to 256 symbols. Otherwise, the security of the internal generator algorithm is not guaranteed, and a generator built from an empty or over-256-symbol alphabet can loop forever instead of returning an ID.

In addition to setting a default size, you can change the ID size when calling the function:

import { customAlphabet } from 'nanoid'
const nanoid = customAlphabet('1234567890abcdef', 10)
model.id = nanoid(5) //=> "f01a2"

Custom Random Bytes Generator

customRandom allows you to create a nanoid and replace alphabet and the default random bytes generator.

In this example, a seed-based generator is used:

import { customRandom } from 'nanoid'

const rng = seedrandom(seed)
const nanoid = customRandom('abcdef', 10, size => {
  return new Uint8Array(size).map(() => 256 * rng())
})

nanoid() //=> "fbaefaadeb"

random callback must accept the array size and return an array with random numbers.

If you want to use the same URL-friendly symbols with customRandom, you can get the default alphabet using the urlAlphabet.

import { customRandom, urlAlphabet } from 'nanoid'
const nanoid = customRandom(urlAlphabet, 10, random)

Note, that between Nano ID versions we may change random generator call sequence. If you are using seed-based generators, we do not guarantee the same result.

Non-Secure

Nano ID uses hardware random bytes generation for security and low collision probability. If you are not so concerned with security, you can use it for environments without hardware random generators.

import { nanoid } from 'nanoid/non-secure'
const id = nanoid() //=> "Uakgb_J5m9g-0JDMbcJqLJ"

Note, that non-secure version is slower than secure. Use it only if you have to.

Usage

React

There’s no correct way to use Nano ID for React key prop since it should be consistent among renders.

function Todos({ todos }) {
  return (
    <ul>
      {todos.map(todo => (
        <li key={nanoid()}>
          {' '}
          /* DON’T DO IT */
          {todo.text}
        </li>
      ))}
    </ul>
  )
}

You should rather try to reach for stable ID inside your list item.

const todoItems = todos.map(todo => <li key={todo.id}>{todo.text}</li>)

In case you don’t have stable IDs you'd rather use index as key instead of nanoid():

const todoItems = todos.map((text, index) => (
  <li key={index}>
    {' '}
    /* Still not recommended but preferred over nanoid(). Only do this if items
    have no stable IDs. */
    {text}
  </li>
))

In case you just need random IDs to link elements like labels and input fields together, useId is recommended. That hook was added in React 18.

React Native

React Native does not have built-in random generator. The following polyfill works for plain React Native and Expo starting with 39.x.

  1. Check react-native-get-random-values docs and install it.
  2. Import it before Nano ID.
import 'react-native-get-random-values'
import { nanoid } from 'nanoid'

PouchDB and CouchDB

In PouchDB and CouchDB, IDs can’t start with an underscore _. A prefix is required to prevent this issue, as Nano ID might use a _ at the start of the ID by default.

Override the default ID with the following option:

db.put({
  _id: 'id' + nanoid(),
  …
})

CLI

You can get unique ID in terminal by calling npx nanoid. You need only Node.js in the system. You do not need Nano ID to be installed anywhere.

$ npx nanoid
npx: installed 1 in 0.63s
LZfXLFzPPR4NNrgjlWDxn

Size of generated ID can be specified with --size (or -s) option:

$ npx nanoid --size 10
L3til0JS4z

Custom alphabet can be specified with --alphabet (or -a) option (note that in this case --size is required):

$ npx nanoid --alphabet abc --size 15
bccbcabaabaccab

TypeScript

Nano ID allows casting generated strings into opaque strings in TypeScript. For example:

declare const userIdBrand: unique symbol
type UserId = string & { [userIdBrand]: true }

// Use explicit type parameter:
mockUser(nanoid<UserId>())

interface User {
  id: UserId
  name: string
}

const user: User = {
  // Automatically casts to UserId:
  id: nanoid(),
  name: 'Alice'
}

Other Programming Languages

Nano ID was ported to many languages. You can use these ports to have the same ID generator on the client and server side.

For other environments, CLI is available to generate IDs from a command line.

Tools

nanoid (ai/nanoid)

Searching Database…

27.1K ·GitHub
Nanoid
What is this?Nano ID is a tiny, secure, URL-friendly unique string ID generator for JavaScript that produces 21-character IDs with collision odds similar to UUID v4.
Is this a library, or can I also run it from the command line?It is mainly a JavaScript library you import into your code, but it also ships a CLI you can run with npx without installing anything.
How do I install and start generating IDs?Install it from npm or JSR (for Deno/Bun), then import nanoid() and call it; for quick one-off IDs in a terminal, just run npx nanoid.
Does it need any extra packages to work?No, Nano ID has zero dependencies and is only 118 bytes minified and brotlied; in React Native you additionally need the react-native-get-random-values polyfill since it lacks a built-in random generator.
Are there any pitfalls when using a custom alphabet?A custom alphabet must contain between 1 and 256 symbols; outside that range the generator's security is not guaranteed and it can even loop forever instead of returning an ID.
Does it work the same in the browser, Node, Deno and React Native?Yes for Node, Deno, Bun and browsers (via npm, JSR, or CDN); React Native needs an extra polyfill since it has no built-in random generator.
Why is Nano ID faster than crypto.randomUUID()?It uses a larger alphabet (A-Za-z0-9-), packing a similar amount of randomness into just 21 characters instead of 36, which the README states makes it 50% faster than native crypto.randomUUID().
Can I use Nano ID outside of JavaScript?Yes, it has been ported to over 20 programming languages including Go, Rust, Python, Java, Swift and more, so you can generate matching IDs across client and server stacks.
Is there a non-secure or seed-based mode?Yes, customRandom lets you plug in your own random bytes generator (e.g. seed-based), and there is also a non-secure build for environments without a hardware random generator, though it is slower.
What are similar projects?npm-check-updates, hono, zx, yargs, deno, hqtui, sharp, twinkleplop
Which topics is it in?deno, toolkit, lightweight, bun, command-line-tool, security, npm, terminal, nodejs, library, typescript, javascript
Creator
ai
Size
5.9 MB
Stars
27.1K
Updated
CommitOct 16Release6.0.2Oct 05
Age
9y
Commits · 90 Days