Kotlin UUID Generator

Generating UUIDs in Kotlin

• UUID.randomUUID().toString() is the idiom, and it produces a lowercase v4 value. Prefer toString() at the boundary and keep the UUID object inside the model: it is comparable and hashable, so it works as a map key and in data classes without custom equality.
• Kotlin/Native and Kotlin/JS have no java.util, so a shared multiplatform module needs an expect fun randomUuid(): String with one actual per target — the JVM one delegating to UUID.randomUUID(), the others drawing from the platform's random source. That indirection is the price of one identifier API across targets.

How to generate

1. Press Generate UUID above to mint a value in this browser — nothing is sent anywhere.
2. Copy one value with Copy, or set How many and use Copy all for a fixture list.
3. Switch Version if your code needs v7 instead of the v4 default, and turn on Formatting to match your stack's conventions.

Use Cases

• Android Room entities — a string primary key assigned before insert, so the row has its identity offline.
• Correlation IDs in structured logs across suspend functions.
• Test fixtures for Kotlin and Android instrumentation tests.

How Kotlin UUID Generator Compares

Code Examples

import java.util.UUID

val id: String = UUID.randomUUID().toString()   // v4
// "8f2c7b41-0d3e-4a55-b6c1-8e7d9f0a1b2c"

// Keep the UUID object in the model; render to string at the edges
data class Order(val id: UUID = UUID.randomUUID(), val total: Long)

// commonMain
expect fun randomUuid(): String

// androidMain / jvmMain
actual fun randomUuid(): String = java.util.UUID.randomUUID().toString()

// nativeMain (Kotlin/Native has no java.util)
actual fun randomUuid(): String = platform.Foundation.NSUUID().UUIDString

Frequently Asked Questions

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