BytePane

UUID (v4) Regex Pattern

Validates a canonical hyphenated UUID v4/GUID string by checking the RFC 9562 version nibble (4) and variant nibble (8, 9, a, or b) in the correct positions.

Reviewed May 31, 2026. Privacy model: tool input is processed in your browser and is not uploaded to BytePane servers.

🔐
Security & Auth
Intermediate
Difficulty
Universal
Language
i
Flags
// Regular Expression
/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i

Live Regex Tester

Pattern Breakdown

^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$
Character class [ ]
Group ( )
Quantifier { }
Anchor ^ $
Repetition * + ?
Escape \
Alternation |
Any char .

Code Examples

JavaScript

const regex = /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i;
const test = "550e8400-e29b-41d4-a716-446655440000";
console.log(regex.test(test)); // true

// Extract matches
const matches = test.match(regex);
console.log(matches);

Python

import re

pattern = r'^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$'
test = "550e8400-e29b-41d4-a716-446655440000"
match = re.search(pattern, test, re.IGNORECASE)
print(match)  # Found!

Go

package main

import (
    "fmt"
    "regexp"
)

func main() {
    re := regexp.MustCompile(`^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$`)
    fmt.Println(re.MatchString("550e8400-e29b-41d4-a716-446655440000")) // true
}

Common Use Cases

ID validationdatabase recordsAPI responses

Match Examples

InputResult
550e8400-e29b-41d4-a716-446655440000Match
550e8400-e29b-51d4-a716-446655440000No Match

UUID v4 regex variants for RFC 9562, GUID braces, compact IDs, and extraction

The base pattern validates canonical hyphenated UUID v4 strings. It checks the fixed version nibble (4) and RFC/IETF variant nibble (8, 9, a, or b). Regex can confirm the shape, but it cannot prove uniqueness, randomness quality, or whether the identifier was generated by a secure source.

VariantPatternUse it when
Canonical UUID v4^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$Use with the i flag for normal API payloads, database IDs, request IDs, and GUID fields stored in 8-4-4-4-12 format.
UUID v4 with optional braces^\{?[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}\}?$Use for systems that may receive Windows or .NET-style GUIDs such as {550e8400-e29b-41d4-a716-446655440000}.
Compact UUID v4 without hyphens^[0-9a-f]{12}4[0-9a-f]{3}[89ab][0-9a-f]{15}$Use only when your system deliberately stores compact 32-character UUIDs with no dashes.
Extract UUID v4 from text\b[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}\bUse without anchors when parsing logs, trace IDs, support tickets, or text that may contain more than one UUID.

Edge cases to test

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

The third group starts with 4 and the fourth group starts with a valid variant nibble.

550e8400-e29b-51d4-a716-446655440000No match

This is not version 4 because the version nibble is 5.

550e8400-e29b-41d4-c716-446655440000No match

The variant nibble c is not valid for the RFC/IETF variant in this v4 pattern.

550E8400-E29B-41D4-A716-446655440000Match with i flag

The page pattern uses the i flag, so uppercase hex is accepted.

{550e8400-e29b-41d4-a716-446655440000}No match in base pattern

Use the optional-braces variant if your input includes surrounding braces.

550e8400e29b41d4a716446655440000No match in base pattern

Use the compact variant only when your data intentionally removes hyphens.

Source checks

RFC 9562 UUID specification: Defines UUID versions and variants, including UUIDv4 as random/pseudorandom UUIDs with fixed version and variant fields.

MDN Crypto.randomUUID(): Documents browser generation of v4 UUIDs using a cryptographically secure random number generator.

UUID GeneratorGenerate secure random UUID v4 identifiers with Web Crypto when available.Regex TesterTest canonical, braced, compact, and extraction variants against real input.JSON Schema ValidatorValidate API payloads that contain UUID string fields.JWT DecoderInspect API tokens and IDs that travel beside UUID-backed user or request identifiers.

About the UUID (v4) Regex

Validates a canonical hyphenated UUID v4/GUID string by checking the RFC 9562 version nibble (4) and variant nibble (8, 9, a, or b) in the correct positions.

Regular expressions (regex) are powerful pattern matching tools used across virtually all programming languages. The uuid (v4) pattern is classified as <strong>intermediate</strong> difficulty in the <strong>security & auth</strong> category. It works in all major programming languages.

When using this regex, always consider edge cases and test thoroughly with real-world data. Use the interactive tester above to validate the pattern against your specific inputs before deploying to production.

More Security & Auth Patterns

JWT Token
Intermediate
→
API Key Pattern
Advanced
→
AWS Access Key
Intermediate
→
Base64 Encoded String
Beginner
→
MD5 Hash
Beginner
→
SHA-256 Hash
Beginner
→
SSH Public Key
Intermediate
→

Need More Regex Patterns?

Browse our complete library of 100+ regex patterns with interactive testers.

All Regex PatternsRegex Tester Tool

Frequently Asked Questions

What is the UUID (v4) regex pattern?

Validates a canonical hyphenated UUID v4/GUID string by checking the RFC 9562 version nibble (4) and variant nibble (8, 9, a, or b) in the correct positions.

How do I use the UUID (v4) regex?

Use the pattern /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i in your code. In JavaScript: new RegExp('^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$', 'i'). Test it above with your own input.

What does this UUID (v4) regex match?

This pattern matches: "550e8400-e29b-41d4-a716-446655440000". It does NOT match: "550e8400-e29b-51d4-a716-446655440000". ID validation, database records, API responses.

Is the UUID (v4) regex beginner-friendly?

This pattern is rated Intermediate. It uses some advanced features like character classes and quantifiers.

What languages support the UUID (v4) regex?

This pattern works in all major programming languages including JavaScript, Python, Java, C#, Go, Ruby, PHP, and more. Syntax may vary slightly between regex engines.

Can I modify the UUID (v4) regex for my use case?

Yes! Use the interactive tester above to modify the pattern and test with your own data. Common modifications include making it case-insensitive (add 'i' flag), matching globally (add 'g' flag), or adjusting character classes.

What is the correct regex for UUID v4?

Use ^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$ with the i flag when you need a canonical hyphenated UUID v4 string. The 4 checks the UUID version and [89ab] checks the RFC/IETF variant nibble.

Does a UUID v4 regex prove that an ID is unique?

No. Regex validates only the text format and fixed version or variant positions. It cannot prove uniqueness, randomness quality, database existence, or whether the UUID was generated by a secure random source.

Should I generate UUID v4 values with regex?

No. Generate UUID v4 values with a proper UUID generator such as crypto.randomUUID() in modern browsers or a trusted server-side UUID library. Use regex only to validate or extract existing UUID strings.

Should UUID v4 be used as a secret token?

Do not treat a UUID format check as a security boundary. UUIDs are identifiers, not authentication secrets. For password reset links, API keys, or session secrets, use purpose-built cryptographic token generation and compare tokens server-side.

Related Tools

JWT Token Regex

Intermediate Security & Auth pattern

API Key Pattern Regex

Advanced Security & Auth pattern

AWS Access Key Regex

Intermediate Security & Auth pattern

Base64 Encoded String Regex

Beginner Security & Auth pattern

MD5 Hash Regex

Beginner Security & Auth pattern

SHA-256 Hash Regex

Beginner Security & Auth pattern