Express 5 User Login API
This guide continues from the User Register API. Make sure you have already implemented user registration, MongoDB connection, User model, and JWT setup. This documentation focuses only on the login flow: validating credentials, verifying hashed passwords, generating JWT tokens, and returning safe user data. No schema or server setup is repeated here.
Auth Module Folder Structure
This shows how login and logout files fit into the existing authentication module created during the register API. Keeping auth logic isolated makes the backend scalable and easy to maintain.
Login Route
Adds a login endpoint to the existing auth routes. This route reuses the same controller file created earlier, keeping all authentication logic in one place.
Login Controller Logic
Handles user login by validating input, checking if the user exists, comparing hashed passwords using bcrypt, generating a JWT token, and returning minimal user data. Passwords are never sent back to the client.
Auth Flow Overview (Register → Login → Logout)
This flow explains how authentication works end-to-end in a real project. Registration creates a user, login issues a JWT, and logout is handled on the client by removing the token.
Related Documents
Express 5 User Register API (Production Ready)
Step-by-step guide to build a secure user registration API using Express 5 (Node.js 22 LTS) and MongoDB. This documentation focuses on real-world project structure: full server setup, proper folder organization, schema design, request validation, password hashing, duplicate user prevention, JWT token generation, and clean error handling. Ideal for beginners who want production-quality code, not just theory.