User Authentication — Letting People Log In
Understand why authentication matters and how to add it to your app with Clerk, Auth.js, or Supabase Auth.
14 min readreal-product, authentication, clerk, auth, security
You've built something cool. It works on your computer. But the moment you want other people to use it — with their own data, their own settings, their own experience — you need authentication.
Authentication is the system that lets users prove who they are (signing in) and ensures they can only access their own stuff (authorization). Without it, every user sees the same data, and anyone can change anything.
This lesson covers why auth matters, the major approaches, and practical guidance on adding it to your vibe-coded project.
Why Authentication Matters
Without authentication:
- All users share the same data
- Anyone can see everyone else's information
- There's no way to save preferences per user
- There's no way to charge users or manage subscriptions
- There's no way to know w
This lesson is part of the Guild Member curriculum. Plans start at $29/mo.