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Nano ID logo by Anton Lovchikov

Build Status Build Status GitHub Issues Go Version Go Ref

This module is a Go implementation of ai/nanoid.

Features of the nanoid spec are:

  • URL friendly
  • Use of hardware random generator
  • Uses a bigger alphabet than UUID, so a similar number of random bits are packed in just 21 chars instead of 36 (like UUID)
  • Much, much faster than UUID (v4)

Features of this specific implementation are:

  • One of the most performant implementations of Nano ID (benchmarks)
  • Prefetches random bytes in advance
  • Uses optimal memory
  • No production dependencies
  • Semver


go get


import (

func main() {
	// The canonic NanoID is nanoid.Standard(21).
	canonicID, err := nanoid.Standard(21)
	if err != nil {

	id1 := canonicID()
	log.Printf("ID 1: %s", id1) // eLySUP3NTA48paA9mLK3V

	// Makes sense to use CustomASCII since 0-9 is ASCII.
	decenaryID, err := nanoid.CustomASCII("0123456789", 12)
	if err != nil {

	id2 := decenaryID()
	log.Printf("ID 2: %s", id2) // 817411560404


See comparison of Nano ID and UUID (V4):

"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"

And also NanoID collision calculator:

If 1,000,000 Nano IDs of length 21 (a.k.a. nanoid.Standard(21)) were generated each second, it would require ~41 thousand years in order to have a 1% probability of a collision

In other words, with 21 characters, the total number of possible unique IDs would be 21^64, which is ~four septenvigintillion (4 followed by 84 zeros) -- a figure larger than the number of atoms that exist in the universe, apparently

Read more here


All benchmarks & tests are in nanoid_test.go.

These are all benchmarks of nanoid.Standard(#)

# of characters & # of IDs benchmark screenshot
8, ~21,800,000
21, ~16,400,000
36, ~11,500,000
255, ~2,500,000


I've tried to make non-secure generation of Nano IDs but removed it because I can't figure out a way to generate many random bytes efficiently with PRNGs.

Credits & references


GNU General Public License v3.0