Semantic Version with 'v' Prefix Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching semantic version with 'v' prefix, 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

# Semantic Version with 'v' Prefix
# ReDoS-safe | RegexVault — Dev & Systems > SemVer

import re

semantic_version_with_v_prefix_pattern = re.compile(r'^[vV]?(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(?:-((?:0|[1-9][0-9]*|[0-9]*[a-zA-Z\-][a-zA-Z0-9\-]*)(?:\.(?:0|[1-9][0-9]*|[0-9]*[a-zA-Z\-][a-zA-Z0-9\-]*))*))?(?:\+([a-zA-Z0-9\-]+(?:\.[a-zA-Z0-9\-]+)*))?$')

def validate_semantic_version_with_v_prefix(value: str) -> bool:
    return bool(semantic_version_with_v_prefix_pattern.fullmatch(value))

# Example
print(validate_semantic_version_with_v_prefix("v1.0.0"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > SemVer 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 v prefix is a convention in Git tagging but not part of SemVer 2.0.0 spec. Strip the v before semantic comparison. Go modules use v+SemVer as their module versioning scheme.