To implement user authentication, choose an authentication method (like JWT or OAuth), set up a secure login system, and manage user sessions.

Implementing user authentication in your web app is crucial for protecting user data and providing personalized experiences. Start by choosing an authentication method that fits your application’s needs. Two popular methods are JSON Web Tokens (JWT) and OAuth. JWT is often used for stateless authentication, allowing you to encode user information in a token that can be verified on the server. OAuth, on the other hand, is commonly used for third-party authentication, enabling users to log in with their existing accounts from services like Google or Facebook. Once you’ve selected your authentication method, set up a secure login system. This typically involves creating a login form where users input their credentials. Ensure that you validate user input to protect against injection attacks, and always hash passwords before storing them in your database using a secure hashing algorithm like bcrypt. After a successful login, generate an authentication token (for JWT) or initiate a session (for traditional methods) to keep the user logged in. Manage user sessions securely by implementing session expiration and allowing users to log out. Ensure that you store sensitive data, such as tokens or session identifiers, securely in cookies with the HttpOnly and Secure flags enabled. Regularly review and update your authentication system to incorporate best practices and protect against emerging threats. Lastly, consider implementing features such as account recovery, email verification, and multi-factor authentication (MFA) to further enhance security and improve the user experience.