nanoid

Nano ID

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

var nanoid = require('nanoid')
model.id = nanoid() //=> "Uakgb_J5m9g~0JDMbcJqLJ"

Safe. It uses cryptographically strong random APIs and guarantees a proper distribution of symbols.

Small. Only 246 bytes (minified and gzipped). No dependencies. It uses Size Limit to control size.

Compact. It uses more symbols than UUID (A-Za-z0-9_~) and has the same number of unique options in just 22 symbols instead of 36.

The generator supports Node.js and all browsers starting from IE 11.

Security

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

Unpredictability

Instead of unsafe Math.random() Nano ID uses crypto module in Node.js and Web Crypto API in browsers.

Uniformity

random % alphabet is a popular mistake to make when coding an ID generator. The spread 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 tests uniformity:

Comparison with UUID

Nano ID is similar to UUID v4 (random-based). It uses same number of random bits in ID, so it has same collision probability:

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

There are only 2 differences between Nano ID and UUID v4:

1. Nano ID uses bigger alphabet for ID, so same random bits are packed just in 22 symbols instead of 36.
2. Code of Nano ID has 2 times smaller size compare to uuid/v4 package: 246 bytes instead of 435.

Usage

Normal

The main module uses URL-friendly symbols (A-Za-z0-9_~) and returns an ID with 22 characters (to have the same uniqueness as UUID v4).

var nanoid = require('nanoid')
model.id = nanoid() //=> "Uakgb_J5m9g~0JDMbcJqLJ"

Symbols -,.() are not encoded in URL, but in the end of a link they could be identified as a punctuation symbol.

Custom Alphabet or Length

If you want to change the ID alphabet or the length you can use low-level generate module.

var generate = require('nanoid/generate')
model.id = generate('1234567890abcdef', 10) //=> "4f90d13a42"

If you want to use the same URL-friendly symbols and just change the length, you can get default alphabet from the url module:

var url = require('nanoid/url')
model.id = generate(url, 10) //=> "Uakgb_J5m9"

Custom Random Bytes Generator

You can replace the default safe random generator using the format module. For instance, to use seed-based generator.

var format = require('nanoid/format')

function random (size) {
  var result = []
  for (var i = 0; i < size; i++) result.push(randomByte())
  return result
}

format(random, "abcdef", 10) //=> "fbaefaadeb"

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