OAuth 2.0 Refresh Token (Generic) Regex for Python

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching oauth 2.0 refresh token (generic), ported and verified for Python. In security-sensitive code, using an unverified regex can open the door to both false positives and denial-of-service attacks. 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

# OAuth 2.0 Refresh Token (Generic)
# ReDoS-safe | RegexVault — Security > OAuth & OIDC

import re

oauth_20_refresh_token_generic_pattern = re.compile(r'^[A-Za-z0-9\-_.+/=]{40,512}$')

def validate_oauth_20_refresh_token_generic(value: str) -> bool:
    return bool(oauth_20_refresh_token_generic_pattern.fullmatch(value))

# Example
print(validate_oauth_20_refresh_token_generic("1//0gBcDeFgHiJkLmNoPqRsTuVwXyZ01234567890aBcDeFgHiJkLmNoPqR"))  # True

Test Cases

When to use this pattern

This pattern is drawn from the Security > OAuth & OIDC 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

Refresh tokens are long-lived (hours to years) credentials used to obtain new access tokens. They must be stored securely (not in localStorage or cookies without Secure/HttpOnly flags). Rotation on use (refresh token rotation) is best practice.