HTTP Status Code Regex for Python

What this pattern does

This page provides a well-structured, multi-part regular expression for matching http status code, 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

# HTTP Status Code
# ReDoS-safe | RegexVault — Web & Network > HTTP

import re

http_status_code_pattern = re.compile(r'^([1-5][0-9]{2})(?:\s+(.+))?$')

def validate_http_status_code(value: str) -> bool:
    return bool(http_status_code_pattern.fullmatch(value))

# Example
print(validate_http_status_code("200"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Web & Network > HTTP 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

Capture group 1 is the status code, group 2 is the optional reason phrase. Note: 6xx and above are not standard. Use application logic to further validate that specific codes are supported (e.g., 418 is valid but 491 is not officially defined).