Generate UUID v4 and v7 in Java

UUID v4 in Java

v4 is purely random — 122 bits of entropy, no structure. Use it when you don't want timing information embedded in the ID, or when you don't care about index locality.

import java.util.UUID;

public class Example {
    public static void main(String[] args) {
        UUID id = UUID.randomUUID(); // v4
        System.out.println(id);
    }
}

UUID v7 in Java

v7 embeds a millisecond Unix timestamp in the first 48 bits, so the IDs sort chronologically. This is what modern databases want from a primary key — sequential inserts land in adjacent index pages instead of scattering writes.

// JDK 25+ ships native UUID v7 via UUID.timeOrderedEpochUUID()
// (October 2025 release). For earlier JDKs, use 'java-uuid-generator':
//
//   <dependency>
//     <groupId>com.fasterxml.uuid</groupId>
//     <artifactId>java-uuid-generator</artifactId>
//     <version>5.0.0</version>
//   </dependency>

import com.fasterxml.uuid.Generators;
import java.util.UUID;

public class Example {
    public static void main(String[] args) {
        UUID id = Generators.timeBasedEpochGenerator().generate();
        System.out.println(id);
    }
}

Notes

`UUID.randomUUID()` uses `SecureRandom` under the hood — same primitive as `Math.random()` is not. Safe for IDs without further work.

Need them in bulk?

Our UUID generator produces 1 to 1000 UUIDs (v4 or v7) instantly, all in your browser, with one-click copy and JSON/CSV export. Useful for seeding test data or pre-generating IDs offline.