What Is a Session? Why Does My App Keep Logging Me Out?
You log in to your app, do some things, come back an hour later, and you have to log in again. Or a user complains that they keep getting logged out even…
You log in to your app, do some things, come back an hour later, and you have to log in again. Or a user complains that they keep getting logged out even though they did not do anything. You built this app with Claude, ChatGPT, Bolt, or Lovable, and the login seemed to work fine in testing. Why does it keep forgetting who people are?
The answer is almost always sessions, and once you understand what they are, the fix becomes clear.
What a Session Actually Is
When you log in to an app, the app needs a way to remember who you are for the duration of your visit. But here is the problem: web browsers and servers do not maintain a persistent connection. Every time you click a link or load a page, your browser makes a fresh request to the server, completely independent of the last one.
Without sessions, you would have to log in on every single page.
A session solves this. When you log in successfully, the server creates a session record, basically a note that says “user Sarah logged in at 2pm.” It gives your browser a session ID, a unique reference number, usually stored as a cookie. Every subsequent request your browser makes includes that session ID. The server sees it, looks up the session record, and knows who you are without you having to log in again.
A session is the short-term memory of your relationship with an app. It lasts for a visit, not forever.
Why Sessions Expire
Sessions are deliberately temporary. A session that never expired would mean anyone who ever logged in to your app on a shared computer would stay logged in permanently, even after walking away. Banks, medical apps, and any service handling sensitive information expire sessions quickly for exactly this reason.
Most sessions are configured to expire after a period of inactivity, anywhere from fifteen minutes for a banking app to thirty days for a social media platform. When the session expires, the server discards the session record. The next time your browser sends the old session ID, the server does not recognise it and treats you as a new visitor.
This is why users get “logged out” without doing anything. Their session timed out.
The Most Common Causes of Unexpected Logouts
Session timeout set too short. The default session duration in many frameworks is short. If your app is logging users out after fifteen minutes of inactivity, the session timeout might just be too aggressive for your use case. Ask your AI: “How do I extend the session timeout in my app so users stay logged in for longer?”
Sessions stored in memory. If your app stores session data in the server’s memory rather than in a database, sessions are lost every time your server restarts. On hosting platforms that sleep inactive apps and wake them on demand, this means sessions are lost every time the app wakes up. Ask your AI: “Is my app storing sessions in memory? If so, how do I move them to the database so they persist across restarts?”
Missing or misconfigured session secret. Sessions are secured with a secret key. If this key is not set in your environment variables, or changes between deployments, all existing sessions become invalid. Ask your AI: “Can you check my session configuration and make sure the session secret is properly set using an environment variable?”
Cookies not being set correctly in production. Sessions rely on cookies, and cookies have settings that affect whether they work across different environments. A common issue is cookies configured to work over HTTP in development but failing silently over HTTPS in production. Ask your AI: “My app works fine locally but users keep getting logged out in production. Can you check the cookie and session settings for potential issues?”
The Difference Between Sessions and Tokens
You may have heard of JWT tokens or access tokens as an alternative to sessions. They solve the same problem differently.
Sessions store the user’s information on the server and give the browser a reference ID. Tokens store the user’s information inside the token itself, which the browser stores and sends with every request. The server does not need to look anything up.
Both approaches work. For most vibe-coded apps, whichever approach your AI chose when building the authentication system is fine. If users are getting logged out unexpectedly, the issue is almost always in the session configuration rather than the choice between sessions and tokens.
The One Thing to Remember
A session is how your app remembers who you are between page loads. It expires after inactivity by design. If users are getting logged out unexpectedly, the most common causes are a session timeout that is too short, sessions stored in memory rather than a database, or a misconfigured session secret. All three are fixable with one conversation with your AI.
Want your app running reliably with authentication that just works? → Snapdock
New here? These might help: What is OAuth? How “Sign In With Google” actually works. → API keys, tokens, and passwords. What is each one and when do you use it? →