UUID generator (v4 and v7)
Generate random v4 or time-ordered v7 identifiers, in bulk.
Result
The result will appear here.Version 4 is 122 random bits and the right default for an identifier that must not be guessable. Version 7 puts a millisecond timestamp in the high bits, so identifiers sort by creation time — which is what keeps a database index from fragmenting when UUIDs become primary keys. Generate either in bulk and paste the block straight into a fixture or a seed script.
How it works
- Randomness comes from crypto.getRandomValues, not Math.random.
- Version and variant bits are set per RFC 9562, so the output validates as a real UUID.
- Generation happens in the page; identifiers are never transmitted.
Where your data goes
Nowhere. This tool runs entirely in your browser: the text you paste is processed by the page and is never transmitted to a server or written to a log.
This tool handles keys and credentials, so nothing about a run is saved, not even to your own history.
What it costs
This tool is free, with no sign-in and no points.
Common questions
- Should I use v4 or v7 as a database key?
- v7, in most cases. Random v4 keys scatter inserts across a B-tree index and fragment it; v7's time prefix keeps inserts at the end of the index, the way an auto-increment key does, while staying globally unique.
- Can two v4 UUIDs collide?
- In principle, and never in practice. At a billion UUIDs a second it would take over a century to reach even a one-in-a-billion chance of a single collision.
- Does v7 leak information?
- It reveals when the identifier was created, to the millisecond. That is usually harmless and occasionally not — if an identifier is exposed publicly and creation time is sensitive, use v4.
The open-source behind it
This tool is a self-contained implementation. uuidjs/uuid (MIT) does the same job as a library — if you need this behaviour inside your own program, start there rather than calling a web page.
uuidjs/uuidAlso known as
- uuid generator
- guid generator
- uuid v4
- uuid v7
- random uuid online