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ai /nanoid

A tiny (108 bytes), secure, URL-friendly, unique string ID generator for JavaScript

9.9K Stars 373 Forks Last release: 4 months ago (3.0.0) MIT License 672 Commits 59 Releases

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Nano ID

Nano ID logo by Anton Lovchikov

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

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

  • Small. 108 bytes (minified and gzipped). No dependencies.Size Limit controls the size.
  • Fast. It is 40% faster than UUID.
  • Safe. It uses cryptographically strong random APIs. Can be used in clusters.
  • Compact. It uses a larger alphabet than UUID (
    ). So ID size was reduced from 36 to 21 symbols.
  • Portable. Nano ID was ported to 14 programming languages.
import { nanoid } from 'nanoid' = nanoid() //=\> "V1StGXR8\_Z5jdHi6B-myT"

Supports modern browsers, IE with Babel, Node.js and React Native.

Sponsored by Evil Martians

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 three 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 code is 3 times less than
    package: 108 bytes instead of 345.
  3. Because of memory allocation tricks, Nano ID is 16% faster than UUID.


$ ./test/benchmark nanoid 655,798 ops/sec customAlphabet 635,421 ops/sec uid.sync 375,816 ops/sec uuid v4 396,756 ops/sec secure-random-string 366,434 ops/sec cuid 183,998 ops/sec shortid 59,343 ops/sec Async: async nanoid 101,966 ops/sec async customAlphabet 102,471 ops/sec async secure-random-string 97,206 ops/sec uid 91,291 ops/sec Non-secure: non-secure nanoid 2,754,423 ops/sec rndm 2,437,262 ops/sec

Test configuration: Dell XPS 2-in-a 7390, Fedora 32, Node.js 13.11.



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

  • Unpredictability. Instead of using the unsafe
    , Nano ID uses the
    module in Node.js and the Web Crypto API in browsers. These modules use unpredictable hardware random generator.
  • Uniformity.
    random % alphabet
    is a popular mistake to make when coding an ID generator. The distribution will not be even; there will be a lower chance for some symbols to appear compared to others. So, it will reduce the number of tries when brute-forcing. Nano ID uses a better algorithmand is tested for uniformity.

Nano ID uniformity

  • Vulnerabilities: to report a security vulnerability, please use the Tidelift security contact. Tidelift will coordinate the fix and disclosure.



The main module uses URL-friendly symbols (


) and returns an ID with 21 characters (to have a collision probability similar to UUID v4).

import { nanoid } from 'nanoid' = nanoid() //=\> "Uakgb\_J5m9g-0JDMbcJqLJ"

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 alphabetor a random generator.


If you support IE, you need to [transpile


]( by Babel and add



// polyfills.js if (!window.crypto) { window.crypto = window.msCrypto }
import './polyfills.js' import { nanoid } from 'nanoid'


Do not call


in the


prop. In React,


should be consistent among renders.

This is the bad example:

<item key="{nanoid()}"></item> /\* DON’T DO IT \*/

This is the good example (


will be generated only once):

const Element = () =\> { const [id] = React.useState(nanoid) return <item key="{id}"></item>}

If you want to use Nano ID in the


prop, you must set some string prefix (it is invalid for the HTML ID to start with a number).

<input id="{'id'" type="text">

Create React App

Create React App has a problemwith ES modules packages.

TypeError: (0 , \_nanoid.nanoid) is not a function

If you have an error above, here is temporary fix:

  1. Use Nano ID 2 instead of 3:
    npm i [email protected]^2.0.0
  2. Vote forpull request, that fix dual packages support.

React Native

React Native does not have built-in random generator.

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

For Expo framework see the next section.


If you use Expo in React Native, you need a different workaround.

  1. Install [
  2. Use
    instead of
  3. Import
    file directly.
import { nanoid } from 'nanoid/async/index.native' async function createUser () { = await 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(), … })


const mySchema = new Schema({ \_id: { type: String, default: () =\> nanoid() } })

ES Modules

Nano ID provides ES modules. You do not need to do anything to use Nano ID as ESM in webpack, Rollup, Parcel, or Node.js.

import { nanoid } from 'nanoid'

For quick hacks, you can load Nano ID from CDN. Special minified


module is available on jsDelivr.

Though, it is not recommended to be used in production because of the lower loading performance.

import { nanoid } from ''

Web Workers

Web Workers do not have access to a secure random generator.

Security is important in IDs when IDs should be unpredictable. For instance, in "access by URL" link generation. If you do not need unpredictable IDs, but you need to use Web Workers, you can use the non‑secure ID generator.

import { nanoid } from 'nanoid/non-secure' nanoid() //=\> "Uakgb\_J5m9g-0JDMbcJqLJ"

Note: non-secure IDs are more prone to collision attacks.


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

If you want to change alphabet or ID size, you should use [



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.

Also, CLI is available to generate IDs from a command line.



To generate hardware random bytes, CPU collects electromagnetic noise. In the synchronous API during the noise collection, the CPU is busy and cannot do anything useful in parallel.

Using the asynchronous API of Nano ID, another code can run during the entropy collection.

import { nanoid } from 'nanoid/async' async function createUser () { = await nanoid() }

Unfortunately, you will lose Web Crypto API advantages in a browser if you the asynchronous API. So, currently, in the browser, you are limited with either security or asynchronous behavior.


By default, Nano ID uses hardware random bytes generation for security and low collision probability. If you are not so concerned with security and more concerned with performance, you can use the faster non-secure generator.

import { nanoid } from 'nanoid/non-secure' const id = nanoid() //=\> "Uakgb\_J5m9g-0JDMbcJqLJ"

Note: your IDs will be more predictable and prone to collision attacks.

Custom Alphabet or Size


allows you to create


with your own alphabet and ID size.

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

Check the safety of your custom alphabet and ID size in ourID collision probability calculator. For more alphabets, check out the options in [



Alphabet must contain 256 symbols or less. Otherwise, the security of the internal generator algorithm is not guaranteed.

Customizable asynchronous and non-secure APIs are also available:

import { customAlphabet } from 'nanoid/async' const nanoid = customAlphabet('1234567890abcdef', 10) async function createUser () { = await nanoid() }
import { customAlphabet } from 'nanoid/non-secure' const nanoid = customAlphabet('1234567890abcdef', 10) = nanoid()

Custom Random Bytes Generator


allows you to create a


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"

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

If you want to use the same URL-friendly symbols with


, you can get the default alphabet using the 



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

Asynchronous and non-secure APIs are not available for



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