PatternRegex

Match a UUID v4

Match version-4 UUIDs precisely: this pattern checks the version digit and variant bits, not just the 8-4-4-4-12 dash layout.

Last updated 4 September 2026

Patterng

[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-4[0-9a-fA-F]{3}-[89abAB][0-9a-fA-F]{3}-[0-9a-fA-F]{12}

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Matches

9b2d8e1a-3f4c-4d5e-9f6a-7b8c9d0e1f2a
AB12CD34-EF56-4A7B-8C9D-0E1F2A3B4C5D

Doesn’t match

12345678-1234-1234-1234-123456789012
9b2d8e1a3f4c4d5e9f6a7b8c9d0e1f2a

Why it’s written this way

The third block must start with 4 — that IS the version field. The fourth block must start with 8, 9, a or b, which is the RFC 4122 variant. Checking both is what distinguishes "a real v4 UUID" from "32 hex digits wearing dashes".

Everything else is plain hex in the standard 8-4-4-4-12 grouping.

Edge cases to know

→Other UUID versions (v1 timestamps, v5 hashes, v7) deliberately fail — drop the two literal checks if you want any-version matching.
→Case-insensitive by character class rather than the i flag, so it behaves the same wherever you paste it.
→The all-zero nil UUID does not match — its version digit is 0.

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