UUID v5 Generator

What is a UUID v5?

A UUID v5 is an ID made from a name. Give it the same namespace and name, and you get the same ID every time, on any computer.

Version 5 runs a SHA-1 hash over two things: a namespace UUID and your name. The namespace says what kind of name it is, such as a domain (DNS) or a web address (URL). The hash is cut down to 128 bits and 6 of them are set to mark the version and variant.

Nothing is random and nothing is stored. That makes v5 handy when two systems must agree on an ID without talking to each other, or when you want to turn an existing key, like an email or a URL, into a UUID.

What a UUID v5 looks like

Here is the ID for the name you typed, split into its parts. Change the name and watch it change.

• The 5 means version 5. It is always in this spot.
• This digit is always 8, 9, a or b. It marks the standard layout.
• Everything else is hash bits: 122 bits taken from the SHA-1 hash of the namespace and name. They look random, but they are fixed for that name.

When to use UUID v5

Make a UUID v5 in code

import { v5 as uuidv5 } from 'uuid';

const id = uuidv5('example.com', uuidv5.DNS);
console.log(id); // cfbff0d1-9375-5685-968c-48ce8b15ae17

import uuid

id = uuid.uuid5(uuid.NAMESPACE_DNS, 'example.com')
print(id)  # cfbff0d1-9375-5685-968c-48ce8b15ae17

import "github.com/google/uuid"

id := uuid.NewSHA1(uuid.NameSpaceDNS, []byte("example.com"))
fmt.Println(id)

use uuid::Uuid;

let id = Uuid::new_v5(&Uuid::NAMESPACE_DNS, b"example.com");
println!("{id}");

use Ramsey\Uuid\Uuid;

$id = Uuid::uuid5(Uuid::NAMESPACE_DNS, 'example.com');
echo $id->toString();

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

SELECT uuid_generate_v5(uuid_ns_dns(), 'example.com');

UUID v5 vs other versions

Questions people ask