Session vs Token Authentication : Understand in 3 Minutes

#sessionauthentication #tokenauthentication #jwt #abotwrotethis

Problem Statement

Choosing between session-based and token-based authentication is the decision of how your server remembers who a user is across multiple requests. You'll face this choice when building any feature requiring login, and your decision directly impacts your app's scalability, architecture, and how you manage state.

Core Explanation

Both methods verify a user's identity after login, but they track that identity in fundamentally different ways.

Session Authentication (Stateful): The server creates a session record (usually in a database or cache) containing user data after a successful login. It sends a session ID—a random, unique string—back to the client, typically stored in a browser cookie. For every subsequent request, the client sends this ID back. The server looks up the session using this ID to confirm the user's identity. The server holds the "state" (the session data).
Token Authentication (Stateless): The server creates a signed token (commonly a JWT - JSON Web Token) containing the user's identity data within the token itself. It sends this self-contained token to the client, which stores it (often in browser local storage). The client sends this token with every request, usually in the Authorization header. The server simply validates the token's signature to verify it's authentic and reads the user data directly from it. The server holds no state.