Data & Formatting · In-Browser Regular Expression Lab

UUID v4 Regex — Validate 128-bit RFC 4122 Canonical UUIDs

Strictly matches version 4 UUIDs with 36 canonical characters including hyphens and version bit 4.

Pattern:

Regular Expression Pattern & Flags

Flags:

//none

Live Test String

Match Found

Load Sample:

Match Inspection & Details1 match

Match #1:c9bf9e57-1685-4c89-bafb-ff5af830be8a

Test Samples Verification Matrix

Expected Valid Samples (Should Match)

c9bf9e57-1685-4c89-bafb-ff5af830be8a Pass

550e8400-e29b-41d4-a716-446655440000 Pass

Expected Invalid Samples (Must Reject)

c9bf9e57-1685-3c89-bafb-ff5af830be8a Rejected (Pass)

not-a-uuid Rejected (Pass)

550e8400-e29b-41d4-a716-44665544000 Rejected (Pass)

Code Implementation Generator

// JavaScript / TypeScript (ES6+)
const pattern = /^[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}$/;
const text = "c9bf9e57-1685-4c89-bafb-ff5af830be8a";

const isMatch = pattern.test(text);
console.log("Is Match:", isMatch);

if (isMatch) {
  const matches = text.match(pattern);
  console.log("Matches:", matches);
}

Regular Expression Token Breakdown

Ensures the 3rd section starts with 4 (version) and the 4th section starts with 8, 9, a, or b (variant 1). Each component of the regular expression serves a distinct syntactical purpose as mapped below:

Token Pattern	Name / Component	Function & Rule
[0-9a-fA-F]{8}	Time-low	8 hexadecimal characters.
[0-9a-fA-F]{4}	Time-mid	4 hexadecimal characters.
4[0-9a-fA-F]{3}	Version 4	Must start with literal digit 4 followed by 3 hex chars.
[89abAB][0-9a-fA-F]{3}	Variant	Variant bits 8, 9, a, or b.
[0-9a-fA-F]{12}	Node	Final 12 hexadecimal characters.