UUID Checker
Check if a UUID/GUID is valid, detect version (v1–v5) and variant (RFC 4122), normalize to canonical form, and extract UUIDs from text — fast, client-side.
How to use
Use it in strict mode for exact canonical UUIDs, or enable extraction to scan text for embedded UUIDs.
- Paste UUIDs (one per line) or any text into the input.
- Optional: enable Extract UUIDs from text to auto-find UUID-like patterns.
- Click Validate to see valid/invalid entries with version and variant.
- Click Normalize to output canonical lowercase UUIDs (valid entries only).
FAQ
What UUID formats does this tool accept?
It accepts canonical UUIDs (8-4-4-4-12), plus optional urn:uuid: prefixes and surrounding braces {...} unless strict mode is enabled.
What does “strict canonical only” mean?
Strict mode requires exactly xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx (hex + hyphens only), with no URN prefix and no braces.
How do you detect the UUID version?
The version is the first hex digit of the 3rd group (for example, 4 in ....-....-4xxx-....-............).
What UUID variant should I expect for RFC 4122?
RFC 4122 UUIDs have the first hex digit of the 4th group in 8, 9, a, or b.
Can I validate multiple UUIDs at once?
Yes—paste one per line (or separated by spaces/commas). The output shows totals and which entries are invalid.
Does this tool send my UUIDs to a server?
No. Validation runs locally in your browser and does not make network requests.
What does “Normalize” do?
It outputs only the valid UUIDs converted to lowercase canonical form, one per line.
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