When I first tried to understand JWT authentication, every article I found either assumed I already knew what a token was or buried the actual implementation under three pages of theory before showing a single line of code.
This guide skips that. We are going to build a working JWT authentication system in Node.js from scratch, understand what is actually happening at each step and end up with something you can use as the foundation for any project that needs user login.
By the end of this article you will have a complete auth flow - user registration, login, protected routes and token verification - with code you actually understand rather than code you copied and hoped for the best.
What JWT Actually Is Before We Touch Any Code
JWT stands for JSON Web Token. It is a way of proving to a server that you are who you claim to be without the server needing to check a database on every single request.
