MIME Type Regex for Python

What this pattern does

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

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

import re

mime_type_pattern = re.compile(r'^(?:application|audio|font|image|model|multipart|text|video|message|x-[a-zA-Z0-9][a-zA-Z0-9!#$&\-^_]{0,30})/[a-zA-Z][a-zA-Z0-9!#$&\-^_.+]{0,100}(?:;\s*[a-zA-Z][a-zA-Z0-9\-]{0,30}=[^;\s]{1,50})*$')

def validate_mime_type(value: str) -> bool:
    return bool(mime_type_pattern.fullmatch(value))

# Example
print(validate_mime_type("text/html"))  # 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

Top-level type is validated against IANA-defined values. x- prefix allows vendor/experimental types. Subtype may include vendor tree (vnd.), personal tree (prs.), or standard tree.