How I Built a Full Authentication System Using React + Node.js

Introduction Building an authentication system is one of the most important steps in creating a secure web application. It controls how users sign up, log in, and access protected content. When I decided to build a full authentication system using React and Node.js, my goal was to keep it simple, secure, and easy to understand. This guide shares the approach I followed, along with practical steps that can help you build your own authentication system from scratch. Understanding the Core Flow Before writing any code, I focused on the basic flow of authentication. A typical system includes: User registration User login Password protection Session or token management Access to protected routes Understanding this flow made it easier to structure both the frontend and backend. Setting Up the Backend with Node.js I started by setting up a Node.js server using Express. This handled all authentication logic and database communication. After initializing the project, I installed essential packa