How to use UUID Validator
The UUID validator checks whether a string is a well-formed UUID and tells you exactly what kind it is. Paste a UUID and it confirms the 8-4-4-4-12 hex layout, reads the version digit to identify whether it is a v1, v3, v4, or v5 UUID, reports the variant, and flags the special nil UUID. It also normalizes surrounding braces and mixed case so you get a canonical, lowercase form. Everything runs in your browser — no UUIDs are sent anywhere.
- Paste a UUID into the input box.
- See whether it is valid and its normalized form.
- Read the reported version and variant.
- Copy the canonical lowercase UUID if you need it.
Your data never leaves your device — 100% private processing.
Anatomy of a UUID
A UUID is a 128-bit identifier written as 32 hexadecimal digits in five groups separated by hyphens: 8-4-4-4-12. Two positions carry meaning beyond randomness. The first digit of the third group is the version, which says how the UUID was generated — version 1 is time-based, versions 3 and 5 are name-based hashes, and version 4 is random. The first digit of the fourth group encodes the variant, which defines the bit layout; almost everything today uses the RFC 4122 variant. This tool parses both fields so you can tell at a glance not just that an ID is valid, but how it was made.
| Version | Basis | Typical use |
|---|---|---|
| v1 | Timestamp + MAC | Ordered IDs |
| v4 | Random | General-purpose IDs |
| v5 | SHA-1 of a name | Deterministic IDs |
Normalizing UUIDs
UUIDs turn up in many surface forms. Some systems wrap them in curly braces, some use uppercase hex, and some mix cases. All of these represent the same underlying value, but a naive string comparison would treat them as different, causing lookups to fail. This tool strips surrounding braces and lowercases the hex to produce the canonical form used by RFC 4122 and most databases. Comparing the normalized output is a reliable way to check whether two differently formatted IDs are actually the same UUID, and it gives you a clean value to store or paste into code without worrying about formatting quirks.
Worked examples
v4
Inputs: f47ac10b-58cc-4372-a567-0e02b2c3d479
Result: Valid · version 4 · RFC 4122
Braced
Inputs: {F47AC10B-...-D479}
Result: Normalized to lowercase, no braces
Nil
Inputs: 00000000-0000-0000-0000-000000000000
Result: Valid · nil UUID
Glossary
- UUID
- A 128-bit universally unique identifier, written as 32 hex digits in an 8-4-4-4-12 layout.
- Version
- A digit in the UUID that indicates how it was generated (time-based, random, or name-based).
- Variant
- Bits that define the UUID’s internal layout; RFC 4122 is the common variant.
- Nil UUID
- The all-zero UUID used as a placeholder or empty value.
Related reading
Frequently Asked Questions
Why use UUID Validator?
- Validates the exact 8-4-4-4-12 UUID format
- Detects the UUID version (v1, v3, v4, v5) and variant
- Recognizes the special nil UUID
- Normalizes braces and case to the canonical lowercase form
Common use cases
- Confirm an ID from a log or database is a valid UUID
- Identify which UUID version a system is generating
- Clean up UUIDs wrapped in braces or in uppercase
- Debug why an ID is being rejected as malformed
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