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UUID Validate Validator🔒 100% local
Validate UUID format. Privacy-first, no server uploads, no tracking.
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Checks a single string against a strict regular expression for a canonical RFC 4122 and RFC 9562 UUID - five hyphenated groups in an 8-4-4-4-12 layout, a version nibble from 1 to 8 and a variant nibble from 8, 9, a or b. On a match it reports the version and variant, the lowercased canonical form and a breakdown of the five structural fields (time_low, time_mid, time_hi, clock_seq, node). The test is a local regex, not a lookup against any registry, and the input never leaves the page.
How to use it
- Paste the candidate UUID into the Input box - the page starts with a standard v4 example.
- Press Process.
- Read the VALID or INVALID verdict, then the Version, Variant and Structure lines underneath.
Worked example
550e8400-e29b-41d4-a716-446655440000becomesVALID RFC 4122 UUID
Version: 4 (random / pseudo-random)
Variant: RFC 4122 (standard)
Canonical: 550e8400-e29b-41d4-a716-446655440000
Structure:
time_low: 550e8400
time_mid: e29b
time_hi: 41d4
clock_seq: a716
node: 446655440000018f4e3a-1c2b-7d4e-8a9b-0123456789abbecomesVALID RFC 4122 UUID
Version: 7 (Unix epoch time + random (RFC 9562))
Variant: RFC 4122 (standard)
Canonical: 018f4e3a-1c2b-7d4e-8a9b-0123456789ab
Structure:
time_low: 018f4e3a
time_mid: 1c2b
time_hi: 7d4e
clock_seq: 8a9b
node: 0123456789aba v7 from RFC 9562, now accepted; the version names cover 1 through 8
00000000-0000-0000-0000-000000000000becomes✗ INVALID — does not match RFC 4122 UUID format.
Expected: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx
M = version (1-8), N = variant (8,9,a,b)the nil UUID and all-f 'max' UUID fail because the version nibble is 0 or f
When to use it
- An API rejected an id and you want to know whether the value was malformed or simply unknown to the server.
- You are confirming that generated test data carries the version and variant your schema expects.
- You need to know which RFC 4122 version a UUID in a log or database column actually is.
What it does not do
- It checks shape only. A UUID can be a syntactically perfect v4 and still be a made-up value or one that does not exist in the system you are talking to.
- The nil UUID 00000000-0000-0000-0000-000000000000 and the all-f 'max' UUID are both rejected, as are urn:uuid: and brace-wrapped forms, because the regex expects the bare hyphenated string with no prefix or padding.
- The variant line can never read anything but 'RFC 4122 (standard)': the regex admits only 8, 9, a or b as the variant nibble, and all four of those ANDed with 0xc give 8, so the NCS and Microsoft branches in the code are unreachable.
- Per-version structural limits, such as a v7's millisecond-precision timestamp, are not checked beyond the version nibble itself.