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SecurityAPIAuth

Access vs Refresh Tokens: The Ultimate Guide

Learn the fundamental differences and how to implement a secure authentication flow in your modern APIs.

Authentication is not just about checking a password. In modern development, session management through tokens is critical for security and scalability.

What is an Access Token?

It is a short-lived token that allows the client to access protected resources.

// Example of a decoded JWT Access Token
{
  "sub": "1234567890",
  "name": "Juan Jimenez",
  "iat": 1516239022,
  "exp": 1516240000 // Expires in 15 minutes
}

Why use Refresh Tokens?

Refresh Tokens allow obtaining a new Access Token without the user having to log in again. This improves UX without sacrificing security.

Best Practices

  1. Don’t store tokens in LocalStorage: They are vulnerable to XSS attacks.
  2. Use HttpOnly Cookies: For the Refresh Token, this is the most secure option.
  3. Token Rotation: Invalidate the old Refresh Token every time you generate a new one.

Secure code is not an option, it is a responsibility.