UUID Validator
Paste a list of UUIDs or GUIDs and see which are valid and why the others are not. The validator checks length, characters, hyphen positions, the RFC 9562 variant and the version, accepts braces and urn:uuid: prefixes unless you choose strict mode, normalises every valid UUID to lower case, and counts versions and duplicates.
- Runs in your browser
- No sign-up
- Free to use
| Input | Result | Version | Normalised |
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How to use UUID Validator
- Paste UUIDs, one per line or separated by commas or spaces.
- Choose strict mode if only the canonical form is acceptable.
- Read the summary and the reason for each invalid entry.
- Copy the valid UUIDs in normalised form, or the invalid ones to fix.
UUID Validator features
Bulk
Up to 5,000 UUIDs at once.
Clear reasons
Wrong length, bad characters, misplaced hyphens, wrong variant or version.
Version counts
How many v1, v4, v7 and other versions the list contains.
Normalisation
Valid UUIDs in canonical lower-case form.
Duplicates
Counts repeated UUIDs.
Strict mode
Accept only 8-4-4-4-12 without braces or prefixes.
When to use UUID Validator
- Cleaning a column of identifiers before import.
- Checking IDs in API payloads or logs.
- Finding malformed GUIDs in configuration files.
- Verifying that generated IDs use the expected version.
UUID Validator FAQ
What makes a UUID valid?
32 hexadecimal digits in groups of 8, 4, 4, 4 and 12, a variant field marking RFC 9562 (the 17th digit 8, 9, a or b) and a known version (1 to 8). The nil and max UUIDs are special valid values.
Are GUIDs the same as UUIDs?
Yes. Microsoft’s GUIDs follow the same format; they are often written in upper case and with braces, which this validator accepts unless strict mode is on.
Why is my UUID invalid even though it looks right?
Usually the variant: random hex strings in UUID shape often have a 17th digit outside 8–b. Such values are not real RFC UUIDs.
Does case matter?
No. UUIDs are case-insensitive; the canonical form is lower case.
How do I check a UUID’s details?
Use the UUID Version Checker, which decodes timestamps and other fields.
Is anything uploaded?
No. Validation runs in your browser.
More than a regular expression
Many systems check UUIDs with a simple pattern of hex digits and hyphens. That accepts strings that are UUID-shaped but not UUIDs, and rejects valid ones written with braces or in upper case. A proper validator separates format from meaning.
The format part checks the 32 hex digits and where the hyphens go. The meaning part reads two fields. The variant, in the high bits of the 17th digit, says which UUID specification applies; RFC 9562, which replaced RFC 4122 in 2024, uses binary 10. The version, the 13th digit, says how the UUID was made: from a time and node (1 and 6), a hash of a name (3 and 5), randomness (4), a Unix timestamp plus randomness (7) or custom data (8).
Bulk validation is useful before importing data, because one malformed identifier can break a foreign key or an API call. The summary shows how many entries are valid, which versions appear and whether duplicates exist, and the copy buttons give clean lists to work with.
Normalising to lower case without braces gives a single representation for comparisons and storage. Databases with a native UUID type do this automatically; in text columns it prevents the same identifier from being stored twice in different forms.