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

use nanoid::nanoid;

fn main() {
   let id = nanoid!(); //=> "Yo1Tr9F3iF-LFHX9i9GvA"
}

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

Compact. It uses a larger alphabet than UUID (A-Za-z0-9_-) and has a similar number of unique IDs in just 21 symbols instead of 36.

[dependencies]
nanoid = "0.5.0"

The main module uses URL-friendly symbols (A-Za-z0-9_-) and returns an ID with 21 characters.

use nanoid::nanoid;

fn main() {
   let id = nanoid!(); //=> "Yo1Tr9F3iF-LFHX9i9GvA"
}

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

If you want to reduce ID length (and increase collisions probability), you can pass the length as an argument generate function:

use nanoid::nanoid;

fn main() {
   let id = nanoid!(10); //=> "IRFa-VaY2b"
}

If you want to change the ID's alphabet or length, you can simply pass the custom alphabet to the nanoid!() macro as the second parameter:

use nanoid::nanoid;

fn main() {
    let alphabet: [char; 16] = [
        '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 'a', 'b', 'c', 'd', 'e', 'f'
    ];

   let id = nanoid!(10, &alphabet); //=> "4f90d13a42"
}

Alphabet must contain 256 symbols or less. Otherwise, the generator will not be secure.

You can replace the default safe random generator by passing your own function as the third argument to nanoid!(). For instance, to use a seed-based generator.

use nanoid::nanoid;

fn random_byte () -> u8 { 0 }

fn main() {
    fn random (size: usize) -> Vec<u8> {
        let mut bytes: Vec<u8> = vec![0; size];

        for i in 0..size {
            bytes[i] = random_byte();
        }

        bytes
    }

    nanoid!(10, &['a', 'b', 'c', 'd', 'e', 'f'], random); //=> "fbaefaadeb"
}

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

If you want to use the same URL-friendly symbols with a custom random source, the default alphabet is exposed as nanoid::alphabet::SAFE:

use nanoid::nanoid;

fn random (size: usize) -> Vec<u8> {
    let result: Vec<u8> = vec![0; size];

    result
}

fn main() {
    nanoid!(10, &nanoid::alphabet::SAFE, random); //=> "93ce_Ltuub"
}

You can use a seeded random generator for reproducible IDs. This is useful for testing or when you need deterministic output.

use nanoid::nanoid;
use rand::{rngs::StdRng, Rng, SeedableRng};

fn main() {
    let mut rng = StdRng::seed_from_u64(42);

    let id = nanoid!(10, &nanoid::alphabet::SAFE, |size| {
        let mut bytes = vec![0u8; size];
        rng.fill(&mut bytes[..]);
        bytes
    });

    println!("{}", id); //=> "wyBwxRa4Xf"
}

The random generator accepts Fn and FnMut closures, allowing you to use stateful random generators. This enables use cases like:

• Seeded RNGs for reproducible IDs
• Custom stateful generators
• Integration with external random sources

Reference implementation on JavaScript.

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
• C#
• C++
• Clojure and ClojureScript
• ColdFusion/CFML
• Crystal
• Dart & Flutter
• Elixir
• Gleam
• Go
• Haskell
• Haxe
• Janet
• Java
• Kotlin
• MySQL/MariaDB
• Nim
• OCaml
• Perl
• PHP
• Python native implementation with dictionaries and fast implementation (written in Rust)
• Postgres Extension and Native Function
• R (with dictionaries)
• Ruby
• Rust
• Swift
• Unison
• V
• Zig