elefcode

Regex pattern

UUID Regex — free online tester

Strict UUID pattern — validates version (1–7) and variant nibbles so random hex strings don't pass.

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The pattern

/[0-9a-f]{8}-[0-9a-f]{4}-[1-7][0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}/gi

How it works

A correct UUID has 32 hex digits laid out as 8-4-4-4-12. This regex goes further: it asserts that the version nibble (13th character) is 1–7 and the variant nibble (17th character) is 8, 9, a, or b — matching the IETF RFC 9562 spec. Case-insensitive so both lowercase and uppercase representations pass.

When to use it

  • ▸Extract UUIDs from log files (especially structured / JSON logs)
  • ▸Validate user input as a UUID before passing to a database
  • ▸Find records by id in unstructured text
  • ▸Pre-flight checks in URL routing

Tip

Add anchors (^ and $) to validate that the entire input is a UUID rather than just contains one.

Try it on this input

Session: 550e8400-e29b-41d4-a716-446655440000   (v4)
User: 7d444840-9dc0-11d1-b245-5ffdce74fad2       (v1)
Trace: 0188aa9b-1234-7abc-89ab-cccccccccccc      (v7)
Bulk: 6ba7b811-9dad-31d1-80b4-00c04fd430c8       (v3)
Bad: 12345, abc-def, 550e8400-e29b-91d4-a716-446655440000 (v9, no such version)
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What this pattern doesn't catch

  • ⚠Does not match the Nil UUID 00000000-0000-0000-0000-000000000000 or Max UUID ff…
  • ⚠Pre-RFC versions (v0, v8) are not matched — adjust the [1-7] class if needed
  • ⚠Doesn't validate that the bytes match a specific implementation (e.g. v4 randomness)

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