My Tools Garage

UUID v5 Generator

Deterministic name-based UUIDs from SHA-1.

in-browser

How to use

  1. 1 Pick a namespace: DNS, URL, OID, X.500, or a custom UUID.
  2. 2 Enter the name to hash inside that namespace.
  3. 3 Read the generated UUID v5 below the inputs.
  4. 4 Copy the UUID and reuse it — the same inputs always reproduce it.

About UUID v5 Generator

The UUID v5 Generator creates name-based universally unique identifiers that are fully deterministic: feed it the same namespace and the same name and it will return the exact same UUID every time, on any machine.

That property makes version-5 UUIDs ideal when you need a stable identifier derived from existing data — a domain name, a URL, an object identifier or any string — rather than a random value that changes on each run.

Under the hood the tool follows RFC 4122 §4.3 precisely.

It concatenates the 16 bytes of the chosen namespace with the UTF-8 bytes of your name, hashes the result with SHA-1, and stamps the version (5) and variant bits into the digest to produce a canonical UUID.

Four predefined namespaces are built in — DNS, URL, OID and X.500 — and you can also paste any custom namespace UUID of your own.

Because v5 UUIDs are reproducible, they are perfect for content addressing, de-duplication, mapping external keys to internal records, and generating consistent IDs across distributed services without coordination.

The entire computation, including the SHA-1 hash, runs locally in your browser using a pure-JavaScript implementation — nothing is uploaded, logged or stored, so it is safe for private or sensitive names and keeps working offline.

FAQ

How is UUID v5 different from v4?

Version 4 UUIDs are random, so they differ every time. Version 5 UUIDs are deterministic — the same namespace and name always produce the same identifier, which is what you want for stable, reproducible IDs.

What hash does UUID v5 use?

UUID v5 uses SHA-1 over the namespace bytes followed by the name. (Version 3 is the same idea but uses MD5.) The version and variant bits are then set per RFC 4122.

Is my name sent anywhere?

No. The namespace lookup and the SHA-1 hash run entirely in your browser, so the name you enter never leaves your device.