Authenticate users in Next.js with Auth.js

Implementing user authentication in a Next.js application using Auth.js and Upstash Redis involves setting up an environment with Node.js and an Upstash account, creating a Next.js app, and configuring the necessary dependencies. This tutorial guides users through the process of setting up a Redis client and defining user types for managing user data. It explains how to create custom authentication providers using Auth.js and Upstash Redis, and how to set up API routes for handling user sign-in and sign-up. The integration includes defining middleware for authentication across the app, utilizing client-side components to manage session state, and building dynamic sign-in and sign-up pages that incorporate security measures like CSRF tokens. By following these steps, developers can efficiently manage user authentication and session data within their Next.js applications, leveraging the serverless capabilities of Upstash Redis.