Next js

Authentication and Authorization In Next Js

What’s the Difference?

Term Meaning
Authentication Verifying who a user is (login/signup).
Authorization Controlling what an authenticated user can do (permissions).

Common Approaches in Next.js

1. Using Third-Party Authentication Providers

  • Use services like Auth0, Firebase Auth, NextAuth.js (popular Next.js-specific library), or OAuth providers (Google, GitHub).

  • These handle login flows, tokens, session management, and user profiles.

Example: NextAuth.js is widely used in Next.js apps.

2. Implementing Authentication Manually

  • Create API routes for login/signup.

  • Store tokens or sessions securely (HTTP-only cookies recommended).

  • Use JWT (JSON Web Tokens) or session IDs.

3. Protecting Pages

  • Client-side: Check user session in React components (e.g., with React Context or hooks).

  • Server-side: Use getServerSideProps or middleware to check authentication before rendering pages.

Example of redirecting unauthenticated users in getServerSideProps:

js
export async function getServerSideProps(context) {
const { req } = context;
const user = req.cookies.userToken; // example cookie check

if (!user) {
return {
redirect: {
destination: '/login',
permanent: false,
},
};
}

return { props: { user } };
}

4. Role-Based Authorization

  • Assign roles (e.g., admin, user).

  • Restrict access or UI features based on roles.

  • Implement logic either client-side or server-side.

5. Using Middleware (Next.js 12+)

  • Middleware can run before rendering, perfect for auth checks and redirects.

  • Define middleware at the root or specific paths.

Example:

js
// middleware.js
import { NextResponse } from 'next/server';

export function middleware(req) {
const token = req.cookies.get('userToken');

if (!token) {
return NextResponse.redirect(new URL('/login', req.url));
}

return NextResponse.next();
}

Summary Table

Aspect How to Implement
Authentication NextAuth.js, Firebase, custom APIs
Authorization Roles, permissions in API or UI
Page Protection getServerSideProps, Middleware, client hooks
Session Management JWT tokens, cookies, HTTP-only cookies

Useful Libraries

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