UUID v5 Generator

About UUID v5 generator

Generates version 5 UUIDs, which are derived from a namespace UUID and a name using SHA-1 rather than chosen at random. The same namespace and name always produce the same identifier, so you can create stable IDs for URLs, hostnames or database keys. Paste one name per line to create a whole batch at once.

How to use it

1. Choose a Namespace: DNS, URL, OID, X.500 or a custom one.
2. For a custom namespace, enter a UUID under Custom namespace UUID, or click Random to make a fresh version 4 value to use as your project's namespace.
3. Type your names into the Names box, one per line. Blank lines and outer whitespace are ignored.
4. Results appear after a short pause, or press Generate UUIDs.
5. Copy an individual row, or use Copy all to take the whole list.

A hostname in the DNS namespace

Namespace: DNS
Name: www.example.com

2ed6657d-e927-568b-95e1-2665a8aea6a2

When to use it

• Giving the same product SKU the same ID in two systems without a lookup table.
• Creating idempotent keys for import jobs so that re-running a job does not duplicate rows.
• Making stable identifiers for URLs or hostnames in a data pipeline.
• Checking that your own code returns the correct v5 value for a known namespace and name.

Questions about UUID v5 generator

How is v5 different from v4?

Version 4 is random, so every call gives a new value. Version 5 is a hash of the namespace and the name, so it is repeatable, and two systems with the same inputs agree without talking to each other.

Why SHA-1 when SHA-1 is considered weak?

The UUID standard specifies it for version 5, and here it only spreads names evenly across the ID space. Collision attacks do not make v5 unsuitable as an identifier, but never treat a UUID as a secret.

What are the four built-in namespaces?

Four fixed UUIDs defined in RFC 4122 for domain names, URLs, ISO object identifiers and X.500 names. Choosing the matching one is convention, but a different namespace gives a different result for the same name.

Are names case-sensitive?

Yes. The name is encoded as UTF-8 and hashed exactly as typed after trimming each line, so Example.com and example.com yield different UUIDs. Normalize names before hashing if that matters to you.

What does the browser need to support?

The WebCrypto API, which is available on secure pages. If it is missing, an error appears instead of a result.

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