This uuid validator checks text you paste. It does not mint a new identifier. Each non-empty line is read as one value. A single line is the same rule as several lines. Blank lines are skipped. More than 50 non-empty lines is an error, and the extra lines are not checked.
A line is first compared with the canonical 8-4-4-4-12 hexadecimal pattern, with hyphens. Uppercase hex is accepted and does not make a value fail. Braces, a urn:uuid: prefix, or hyphens in the wrong places fail as structure, with that reason, rather than a bare word “invalid” and nothing else.
When the shape matches, the page reads the version nibble and the variant nibble. The nil UUID, all zeros, is accepted and reported as nil for both fields. Any other value needs a version nibble from 1 through 8 and the RFC 4122 variant, which is the nibble 8, 9, a, or b. A version nibble of 0 on a non-nil value is rejected with the nibble named. An NCS, Microsoft, or reserved variant is rejected with the nibble and the variant name. Version 4 is not required. A version 1 value with the RFC variant is valid here, and the report says version 1. The page does not claim that every version means the same thing.
Nothing in the result is a uniqueness check. A value can be well formed and still be a sample that appears in a thousand blog posts. The status says the page does not generate UUIDs and does not claim they are unique. Generation stays on the UUID Generator, which emits version 4 only.
The input cap is 200,000 characters, and the practical cap is 50 lines. Empty input, or a box that is only blank lines, is an error.
A lowercase or uppercase version 4 value with variant a, such as the familiar 8-4-4-4-12 sample that starts its third group with 4 and its fourth group with a, is reported as valid, version 4, variant RFC 4122. The nil value is valid, version nil, variant nil. A version 1 value with the same variant family is valid, version 1. 1234 fails the shape. A value whose version nibble is 0, and that is not nil, fails the version check. A value whose variant nibble is 7 fails the variant check.
00000000-0000-0000-0000-000000000000When you need a new version 4 value, use the UUID Generator. Bring the result back here if you want it checked. This page will not grow a Generate button. The two tools are linked in that direction so the jobs stay separate.
The report lowercases nothing in your input box. The result lines describe the value. They do not rewrite it into a second format without hyphens. If a database stores 32 hex digits and no hyphens, this page will call that line a structure error. Add the hyphens if you want the canonical check, or accept that the other layout is out of scope.
Version 7 and the other allowed nibbles pass the same structural test. The page does not explain the time layout of version 7 or the node layout of version 1 beyond naming the version. Those layouts are not the same, and a green line must not be read as “this is a random version 4.”
Clear removes the list and the report. The page does not keep a history of values you checked.
Checks the 8-4-4-4-12 hex form, the version nibble (1–8), and the RFC 4122 variant. Uppercase is accepted. The nil UUID is accepted and reported as nil. Other versions are not treated as version 4. At most 50 non-empty lines. This page does not generate UUIDs.
No. Use the UUID Generator when you need a new version 4 value. This page only checks text you already have.
No. Version nibbles 1 through 8 are accepted when the variant is RFC 4122. The report names the version it found.
No. All zeros is accepted and labeled nil for both version and variant.
No. The check is about shape, version, and variant. It says nothing about uniqueness or who minted the value.