UUID Validator
Paste a UUID to check whether it's well-formed and see its version and variant, or validate a whole list at once.
Last updated
Mode
What each UUID version means
How to validate a UUID
- Paste a UUID, or choose Bulk and paste a list, one per line.
- See whether each one is valid, and its version and variant.
- If one is invalid, the reason is shown: wrong length, missing hyphens or bad characters.
About this tool
A UUID's canonical text form is 32 hex digits split into five groups (8-4-4-4-12). Two of those digits carry structural information: the first digit of the third group is the version (which algorithm created it), and the first digit of the fourth group encodes the variant — almost every UUID you'll see in the wild uses the RFC 4122 / RFC 9562 variant, indicated by that digit starting with binary 10 (hex 8, 9, a, or b).
This validator checks the overall shape first — 32 hex characters, hyphens in the right places — and if that's wrong it tells you specifically what's off (wrong length, missing hyphens, invalid characters) rather than just "invalid". If the shape is fine, it decodes the version and variant nibbles and explains what they mean, including the special all-zero Nil UUID and all-one Max UUID sentinels from RFC 9562.
Bulk mode runs the same check against every line of a pasted list and shows a pass/fail table with the version, variant, and reason for each row, so you can spot bad entries in a large dataset at a glance.
Everything runs locally in your browser; nothing you paste is uploaded anywhere.
Questions about UUID versions
How do I tell which version a UUID is?
Look at the first digit of the third group: in 018f4e2b-7c3e-7a3e-…, the 7 means version 7. Paste it here to have it decoded and explained.
What is the difference between UUID v4 and v7?
Version 4 is entirely random. Version 7 starts with a timestamp, so new IDs sort in creation order, which suits database keys.
What is the nil UUID?
00000000-0000-0000-0000-000000000000, a special value meaning “no UUID”. The all-f Max UUID is another special value.
Can I check a whole column of IDs?
Yes. Paste them in Bulk mode to get a pass or fail table with the reason for each line.