UUID v1 Generator

What is a UUID v1?

A UUID v1 is a 36-character ID built from the time it was made and a node ID, which in the original design came from the network card of the computer.

The time is a 60-bit count of 100-nanosecond steps since 15 October 1582, the day the Gregorian calendar began. A 14-bit clock sequence guards against repeats if the clock jumps back, and the last 12 digits are the 48-bit node ID.

Older systems used the computer's MAC address as the node, so every ID showed which machine made it. This generator does not. It uses a random node ID with the multicast bit set, as RFC 9562 allows, so your MAC address is never used. Web pages cannot read it anyway.

Version 1 is now a legacy format. Its time digits are stored lowest part first, so v1 IDs do not sort by time. For new work, the standard recommends UUID v7.

What a UUID v1 looks like

Here is the ID you just made, split into its parts. ClickTap Generate above and watch it change.

• The time it was made, split across three groups with the lowest part first.
• The 1 means version 1. It is always in this spot.
• This digit is always 8, 9, a or b. It marks the standard layout.
• The clock sequence, a number that guards against repeats if the clock goes back.
• The node ID. Here it is random with the multicast bit set, not your MAC address.

Its time part says it was made at the moment you opened this page.

When to use UUID v1

Make a UUID v1 in code

import { v1 } from 'uuid';

const id = v1();
console.log(id);

import uuid

id = uuid.uuid1()
print(id)

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

UUID id = Generators.timeBasedGenerator().generate();
System.out.println(id);

import "github.com/google/uuid"

id, err := uuid.NewUUID()
if err != nil {
	panic(err)
}
fmt.Println(id)

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

SELECT uuid_generate_v1mc();

SELECT UUID();

UUID v1 vs other versions

Questions people ask