# Nano ID Nano ID logo by Anton Lovchikov **English** | [日本語](./README.ja.md) | [Русский](./README.ru.md) | [简体中文](./README.zh-CN.md) | [Bahasa Indonesia](./README.id-ID.md) | [한국어](./README.ko.md) | [العربية](./README.ar.md) 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.** 118 bytes (minified and brotlied). No dependencies. [Size Limit] controls the size. - **Fast.** 50% faster than native `crypto.randomUUID()`. - **Safe.** It uses hardware random generator. Can be used in clusters. - **Short IDs.** It uses a larger alphabet than UUID (`A-Za-z0-9_-`). So ID size was reduced from 36 to 21 symbols. - **Portable.** Nano ID was ported to over [20 programming languages](./README.md#other-programming-languages). ```js import { nanoid } from 'nanoid' model.id = nanoid() //=> "V1StGXR8_Z5jdHi6B-myT" ``` ---   Made at Evil Martians, product consulting for developer tools. --- [Size Limit]: https://github.com/ai/size-limit ## Table of Contents - [Table of Contents](#table-of-contents) - [Comparison with UUID](#comparison-with-uuid) - [Benchmark](#benchmark) - [Security](#security) - [Install](#install) - [JSR](#jsr) - [CDN](#cdn) - [API](#api) - [Custom Alphabet or Size](#custom-alphabet-or-size) - [Custom Random Bytes Generator](#custom-random-bytes-generator) - [Non-Secure](#non-secure) - [Usage](#usage) - [React](#react) - [React Native](#react-native) - [PouchDB and CouchDB](#pouchdb-and-couchdb) - [CLI](#cli) - [TypeScript](#typescript) - [Other Programming Languages](#other-programming-languages) - [Tools](#tools) ## 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 ```rust $ 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)]_ - **Unpredictability.** Instead of using the unsafe `Math.random()`, Nano ID uses the `crypto` 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 algorithm] and is tested for uniformity. Nano ID uniformity - **Well-documented:** all Nano ID hacks are documented. See comments in [the source]. - **Vulnerabilities:** to report a security vulnerability, please use the [Tidelift security contact](https://tidelift.com/security). Tidelift will coordinate the fix and disclosure. [Secure random values (in Node.js)]: https://gist.github.com/joepie91/7105003c3b26e65efcea63f3db82dfba [better algorithm]: https://github.com/ai/nanoid/blob/main/index.js [the source]: https://github.com/ai/nanoid/blob/main/index.js ## Install ```bash npm install nanoid ``` ### JSR [JSR](https://jsr.io) is a replacement for npm with open governance and active development (in contrast to npm). ```bash npx jsr add @sitnik/nanoid ``` You can use it in Node.js, Deno, Bun, etc. ```js // 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. ```js 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). ```js 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. ```js 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](#custom-alphabet-or-size) or a [random generator](#custom-random-bytes-generator). [ID collision probability]: https://zelark.github.io/nano-id-cc/ ### Custom Alphabet or Size `customAlphabet` returns a function that allows you to create `nanoid` with your own alphabet and ID size. ```js import { customAlphabet } from 'nanoid' const nanoid = customAlphabet('1234567890abcdef', 10) model.id = nanoid() //=> "4f90d13a42" ``` ```js 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 256 symbols or less. Otherwise, the security of the internal generator algorithm is not guaranteed. In addition to setting a default size, you can change the ID size when calling the function: ```js import { customAlphabet } from 'nanoid' const nanoid = customAlphabet('1234567890abcdef', 10) model.id = nanoid(5) //=> "f01a2" ``` [`nanoid-dictionary`]: https://github.com/CyberAP/nanoid-dictionary ### 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: ```js 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`. ```js 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. ```js 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. ```jsx function Todos({ todos }) { return ( ) } ``` You should rather try to reach for stable ID inside your list item. ```jsx const todoItems = todos.map(todo =>
  • {todo.text}
    • ) ``` In case you don’t have stable IDs you'd rather use index as `key` instead of `nanoid()`: ```jsx const todoItems = todos.map((text, index) => (
  • {' '} /* Still not recommended but preferred over nanoid(). Only do this if items have no stable IDs. */ {text}
    • )) ``` 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. [`useId`]: https://react.dev/reference/react/useId ### 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. ```js import 'react-native-get-random-values' import { nanoid } from 'nanoid' ``` [`react-native-get-random-values`]: https://github.com/LinusU/react-native-get-random-values ### 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: ```js 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. ```sh $ npx nanoid npx: installed 1 in 0.63s LZfXLFzPPR4NNrgjlWDxn ``` Size of generated ID can be specified with `--size` (or `-s`) option: ```sh $ npx nanoid --size 10 L3til0JS4z ``` Custom alphabet can be specified with `--alphabet` (or `-a`) option (note that in this case `--size` is required): ```sh $ npx nanoid --alphabet abc --size 15 bccbcabaabaccab ``` ### TypeScript Nano ID allows casting generated strings into opaque strings in TypeScript. For example: ```ts declare const userIdBrand: unique symbol type UserId = string & { [userIdBrand]: true } // Use explicit type parameter: mockUser(nanoid()) 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. - [C](https://github.com/lukateras/nanoid.h) - [C#](https://github.com/codeyu/nanoid-net) - [C++](https://github.com/mcmikecreations/nanoid_cpp) - [Clojure and ClojureScript](https://github.com/zelark/nano-id) - [ColdFusion/CFML](https://github.com/JamoCA/cfml-nanoid) - [Crystal](https://github.com/mamantoha/nanoid.cr) - [Dart & Flutter](https://github.com/pd4d10/nanoid-dart) - [Elixir](https://github.com/railsmechanic/nanoid) - [Gleam](https://github.com/0xca551e/glanoid) - [Go](https://github.com/matoous/go-nanoid) - [Haskell](https://github.com/MichelBoucey/NanoID) - [Haxe](https://github.com/flashultra/uuid) - [Janet](https://sr.ht/~statianzo/janet-nanoid/) - [Java](https://github.com/wosherco/jnanoid-enhanced) - [Kotlin](https://github.com/viascom/nanoid-kotlin) - [MySQL/MariaDB](https://github.com/viascom/nanoid-mysql-mariadb) - [Nim](https://github.com/icyphox/nanoid.nim) - [OCaml](https://github.com/routineco/ocaml-nanoid) - [Perl](https://github.com/tkzwtks/Nanoid-perl) - [PHP](https://github.com/hidehalo/nanoid-php) - Python [native](https://github.com/puyuan/py-nanoid) implementation with [dictionaries](https://pypi.org/project/nanoid-dictionary) and [fast](https://github.com/oliverlambson/fastnanoid) implementation (written in Rust) - Postgres [Extension](https://github.com/spa5k/uids-postgres) and [Native Function](https://github.com/viascom/nanoid-postgres) - [R](https://github.com/hrbrmstr/nanoid) (with dictionaries) - [Ruby](https://github.com/radeno/nanoid.rb) - [Rust](https://github.com/nikolay-govorov/nanoid) - [Swift](https://github.com/ShivaHuang/swift-nanoid) - [Unison](https://share.unison-lang.org/latest/namespaces/hojberg/nanoid) - [V](https://github.com/invipal/nanoid) - [Zig](https://github.com/SasLuca/zig-nanoid) For other environments, [CLI] is available to generate IDs from a command line. [CLI]: #cli ## Tools - [ID size calculator] shows collision probability when adjusting the ID alphabet or size. - [`nanoid-dictionary`] with popular alphabets to use with [`customAlphabet`]. - [`nanoid-good`] to be sure that your ID doesn’t contain any obscene words. [`nanoid-dictionary`]: https://github.com/CyberAP/nanoid-dictionary [ID size calculator]: https://zelark.github.io/nano-id-cc/ [`customAlphabet`]: #custom-alphabet-or-size [`nanoid-good`]: https://github.com/y-gagar1n/nanoid-good