How to use the UUID Generator tool
- Pick the version: v4 (random) or v7 (time-ordered).
- Choose how many and the format options.
- Click “Generate”, then copy or download the list. Paste any UUID below to decode it.
v4 or v7?
UUID v4 is 122 random bits. It is the most widely supported version and reveals nothing about when or where it was made.
UUID v7, standardised in RFC 9562 (2024), starts with a 48-bit Unix timestamp in milliseconds followed by random bits. Because new values sort after old ones, they make much better primary keys: database indexes stay compact and inserts stay fast, whereas random v4 keys scatter writes across the whole index. If you are designing a new table, v7 is usually the better choice. The only trade-off is that the creation time can be read from the ID.
Format and compatibility
- GUID and UUID are the same thing; Microsoft tools often show them in uppercase and with braces.
- Store UUIDs in a native type where possible (uuid in PostgreSQL, BINARY(16) in MySQL) rather than as 36-character text.
- The generator uses the browser’s secure random number generator (crypto.getRandomValues), the same source used for encryption keys.
Privacy
Everything runs in your browser. Nothing you type is sent to our server or stored.
Frequently asked questions
Can two UUIDs ever be the same?
In theory yes, in practice no: you would need to generate about a billion v4 UUIDs per second for 85 years for a 50 percent chance of one collision.
Are the v7 UUIDs in order?
Yes. UUIDs generated in one batch are strictly increasing, even within the same millisecond.
Can I get the time from a v4 UUID?
No, v4 contains no time. Versions 1, 6 and 7 do, and the decoder shows it.
What is the nil UUID?
00000000-0000-0000-0000-000000000000, a special value meaning “no UUID”.