Kotlin Multiplatform NanoId

A unique string ID generator for Javascript, JVM and Native written in Kotlin.

Secure

KMP-NanoId uses Korlibs Krypto SecureRandom to generate cryptographically strong random IDs with a proper distribution of characters.

Krypto provides a SecureRandom class that extends the kotlin.random.Random class, but generating cryptographic secure values.

It uses SecureRandom on the JVM + PRNGFixes on Android. On Native POSIX (including Linux, macOs and iOS), it uses /dev/urandom, on Windows BCryptGenRandom

Compact

KMP-NanoId generates compact IDs with just 21 characters.

By using a larger alphabet than UUID, KMP-NanoId can generate a greater number of unique IDs, when compared to UUID, with fewer characters (21 vs 36)

URL-Friendly

KMP-NanoId uses URL-friendly character (A-Za-z0-9_-). Perfect for unique identifiers in web applications.

Customizable

KMP-NanoId is fully customizable.

All default options may be overridden. Supply your own Random Number Generator, alphabet or size.

Tested

KMP-NanoId is thoroughly tested with Kotlin Test

Usage

KMP-NanoId provides one easy-to-use utility class (NanoIdUtils) with multiple methods to generate IDs.

Standard IDs - randomNanoId()

The default method creates secure, url-friendly, unique ids. It uses a url-friendly alphabet (A-Za-z0-9_-), a secure random number generator, and generates a unique ID wit 21 characters.

Java:

String id = NanoIdUtils.randomNanoId();

Kotlin:

val id = NanoIdUtils.randomNanoId()

Custom IDs - NanoIdUtils.randomNanoId(random, alphabet, size)

Additional methods allow you to generate custom IDs by specifying your own random number generator, alphabet or size.

Java:

Methods created by @JvmOverloads

Random random = new Random();
char[] alphabet = {'a', 'b', 'c'};
int size = 10;

// Only change random number generator
String idRandom = NanoIdUtils.randomNanoId(random);

// Change random number generator and alphabet
String idRandomAlphabet = NanoIdUtils.randomNanoId(random, alphabet);

// Change all parameter
String idRandomAlphabetSize = NanoIdUtils.randomNanoId(random, alphabet, size);

Kotlin:

val kRandom = Random()
val kAlphabet = charArrayOf('a', 'b', 'c')
val kSize = 10

// Only change random number generator
val idRandom = NanoIdUtils.randomNanoId(kRandom)

// Change random number generator and alphabet
val idRandomAlphabet = NanoIdUtils.randomNanoId(kRandom, kAlphabet)

// Change all parameter
val idRandomAlphabetSize = NanoIdUtils.randomNanoId(kRandom, kAlphabet, kSize)

// Change alphabet only (keep default random number generator and size)
val idAlphabet = NanoIdUtils.randomNanoId(alphabet = kAlphabet)

// Change size only (keep default random number generator and alphabet)
val idSize = NanoIdUtils.randomNanoId(size = kSize)

// Change alphabet and size (keep default random number generator)
val idAlphabetSize = NanoIdUtils.randomNanoId(alphabet = kAlphabet, size = kSize)

Needed in Java (can be used in Kotlin)

Default values:

// Useful to keep some default values and change only specific
NanoIdUtils.DEFAULT_NUMBER_GENERATOR
NanoIdUtils.DEFAULT_ALPHABET
NanoIdUtils.DEFAULT_SIZE

// Usage example
String idAlphabet = NanoIdUtils.randomNanoId(Random(), NanoIdUtils.DEFAULT_ALPHABET, 10);

License

Code released under the MIT License

Other Programming Languages

• C#
• Clojure and ClojureScript
• Crystal
• Dart
• Go
• Elixir
• Haskell
• Java
• JavaScript
• Nim
• PHP
• Python
• Ruby
• Rust
• Swift

Also, a CLI tool is available to generate IDs from the command line.