UUID v4 Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching uuid v4, ported and verified for Python. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Python project — whether you're validating in a Django view, a FastAPI endpoint, or a standalone data processing script.

Python Implementation

# UUID v4
# ReDoS-safe | RegexVault — Web & Network > Misc

import re

uuid_v4_pattern = re.compile(r'^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$')

def validate_uuid_v4(value: str) -> bool:
    return bool(uuid_v4_pattern.fullmatch(value))

# Example
print(validate_uuid_v4("550e8400-e29b-41d4-a716-446655440000"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > Misc category and carries a ReDoS-safe certification. That matters for Python developers because particularly important in Python web servers where CPU-bound regex operations can stall concurrent request handling. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

The 4 in position 13 (version) and the [89ab] in position 17 (variant) are the defining characteristics of UUID v4. The i flag allows uppercase hex.