Content-Type MIME Type Regex for Python

What this pattern does

This page provides a comprehensive, battle-tested regular expression for matching content-type mime type, 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

# Content-Type MIME Type
# ReDoS-safe | RegexVault — Web & Network > HTTP

import re

contenttype_mime_type_pattern = re.compile(r'^[a-zA-Z][a-zA-Z0-9!#$&\-^_]{0,59}/[a-zA-Z][a-zA-Z0-9!#$&\-^_.+]{0,59}(?:;\s*[a-zA-Z][a-zA-Z0-9\-]{0,49}=[^;\s]{1,100})*$')

def validate_contenttype_mime_type(value: str) -> bool:
    return bool(contenttype_mime_type_pattern.fullmatch(value))

# Example
print(validate_contenttype_mime_type("application/json"))  # 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

Parameters use name=value format separated by semicolons. The charset parameter is the most common. IANA maintains the media type registry.