A tiny, secure, URL-friendly unique string ID generator for Clojure and ClojureScript.

• Secure. It uses cryptographically strong random APIs.
• Compact. It uses a larger alphabet than UUID (A-Za-z0-9_-). So ID size was reduced from 36 to 21 symbols.
• URL-Friendly. It uses only URL-friendly characters. Perfect for unique identifiers in web applications.

clj -Sdeps '{:deps {nano-id/nano-id {:mvn/version "1.1.0"}}}'

(require '[nano-id.core :refer [nano-id]])
(nano-id) ;; => "trxwfoC8mqB3Q8Wrdq4OQ"

$ lein bench

## Actually, you will get more detailed info, this is summary of 3 runs.

UUID               0.29µs 0.29µs 0.30µs
nano-id            0.43µs 0.44µs 0.43µs
jnanoid            0.64µs 0.66µs 0.65µs
nano-id (custom)   0.62µs 0.62µs 0.62µs
jnanoid (custom)   0.65µs 0.65µs 0.68µs

Configuration:

• MacBook Pro (16-inch, 2019), 2,3 GHz 8-Core Intel Core i9, 32 GB 2667 MHz DDR4;
• OpenJDK Runtime Environment Temurin-11.0.22+7 (build 11.0.22+7);
• Clojure 1.11.1.

nano-id/nano-id {:mvn/version "1.1.0"}

[nano-id "1.1.0"]

The default implementation uses 64-character alphabet and generates 21-character IDs.

user=> (require '[nano-id.core :refer [nano-id]])
nil

user=> (nano-id)
"NOBHihn110UuXbF2JiKxT"

If you want to reduce the ID size (and increase collision probability), you can pass the size as an argument.

user=> (nano-id 10)
"N2g6IlJP0l"

Don’t forget to check the safety of your ID size via collision probability calculator.

For IE support, you need to add crypto alias:

(ns your-app.polyfills)

(when-not (exists? js/crypto)
  (set! js/crypto js/msCrypto))

(ns your-app.core
  (:require [your-app.polyfills]
            [nano-id.core :refer [nano-id]]))

If your target is node, use @peculiar/webcrypto polyfill:

(ns your-app.polyfills
  (:require ["@peculiar/webcrypto" :refer [Crypto]]))

(set! js/crypto (Crypto.))

(ns your-app.core
  (:require [your-app.polyfills]
            [nano-id.core :refer [nano-id]]))

If for whatever reason the default implementation doesn't fit your project, you can build your own ID generator just passing your alphabet and ID size in custom function. It will give you back a new generator:

user=> (require '[nano-id.core :refer [custom]])
nil

user=> (def my-nano-id (custom ".-" 6))
#'user/my-nano-id

user=> (my-nano-id)
"-.---."

Also you can provide your random bytes generator. In the example below we use this feature to encode the current time:

(let [alphabet "-0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz"
      time-gen (fn [n]
                 (->> (quot (System/currentTimeMillis) 1000)
                      (iterate #(unsigned-bit-shift-right % 6))
                      (take n)
                      reverse
                      byte-array))
      time-id  (custom alphabet 6 time-gen)]
  (time-id))
"0TfMui"

This encodes current time using a lexicographical alphabet.

• Nano ID Collision Calculator

You can find implementations in other programming languages here.

Nano ID.