UUID Generator
Unique IDs for databases, APIs, files and test data. Random v4, time-ordered v7 (best for database keys), and every other version in RFC 9562, one at a time or in bulk.
- Made in your browser
- Cryptographically random
- Up to 10,000 at once
Bulk generate
Decode a UUID
Paste any UUID or GUID to check it's valid and see its version, and when it was made if it contains a time.
Which version should I use?
- v4 (random): the default almost everywhere. 122 random bits, so you'd need to make billions a second for decades to expect a duplicate.
- v7 (time-ordered): best for database primary keys. It starts with the time in milliseconds, so new rows go at the end of the index instead of scattering, which keeps inserts fast. It does reveal when it was created.
- v5 (name-based): the same namespace and name always give the same UUID, which is useful for stable IDs made from URLs or domain names. v3 is the older MD5 version; prefer v5.
- v1 and v6: older time-based versions. We use a random node ID instead of your network card's address, as RFC 9562 recommends. Use v7 for new systems.
Good to know
- UUIDs and GUIDs are the same thing. Microsoft often shows GUIDs in upper case and in {braces}.
- Everything is generated in your browser with its cryptographic random number generator. Nothing is sent to our server.
- UUIDs aren't secrets. Don't use them as passwords, reset links or API keys on their own: use a proper random token or password generator for those.
- Several v7 UUIDs made in the same millisecond still sort in the order they were made, using a counter (RFC 9562 method 1).