UUID v8 Generator

const b = crypto.getRandomValues(new Uint8Array(16));
b[6] = (b[6] & 0x0f) | 0x80; // version 8
b[8] = (b[8] & 0x3f) | 0x80; // variant
const hex = [...b].map((x) => x.toString(16).padStart(2, '0')).join('');
const id = [hex.slice(0, 8), hex.slice(8, 12), hex.slice(12, 16), hex.slice(16, 20), hex.slice(20)].join('-');
console.log(id);

Built into browsers and Node.js. The uuid package has no v8 function, since the layout is yours. Put your own bits in b.

import secrets
import uuid

id = uuid.uuid8(secrets.randbits(48), secrets.randbits(12), secrets.randbits(62))
print(id)

uuid8() is built in from Python 3.14. It takes your own 48, 12 and 62-bit values. Its default random values are not secure, so this passes values from secrets.

import java.nio.ByteBuffer;
import java.security.SecureRandom;
import java.util.UUID;

byte[] b = new byte[16];
new SecureRandom().nextBytes(b);
b[6] = (byte) ((b[6] & 0x0f) | 0x80); // version 8
b[8] = (byte) ((b[8] & 0x3f) | 0x80); // variant
ByteBuffer buf = ByteBuffer.wrap(b);
UUID id = new UUID(buf.getLong(), buf.getLong());
System.out.println(id);

Built into Java, no library needed. Put your own bits in b before building the UUID.

using System.Security.Cryptography;

byte[] b = RandomNumberGenerator.GetBytes(16);
b[6] = (byte)((b[6] & 0x0F) | 0x80); // version 8
b[8] = (byte)((b[8] & 0x3F) | 0x80); // variant
Guid id = new Guid(b, bigEndian: true);
Console.WriteLine(id);

Needs .NET 8 or later for bigEndian, which keeps the bytes in standard order.

import (
	"crypto/rand"

	"github.com/google/uuid"
)

var id uuid.UUID
rand.Read(id[:])
id[6] = id[6]&0x0f | 0x80 // version 8
id[8] = id[8]&0x3f | 0x80 // variant
fmt.Println(id)

Uses crypto/rand for the bits and the google/uuid type to print them.

SELECT overlay(gen_random_uuid()::text placing '8' from 15 for 1)::uuid;

Swaps the version digit of a random v4 for 8. gen_random_uuid() is built in since PostgreSQL 13.