| name | auth-patterns |
| description | This skill should be used when the user asks about "authentication in Next.js", "NextAuth", "Auth.js", "middleware auth", "protected routes", "session management", "JWT", "login flow", or needs guidance on implementing authentication and authorization in Next.js applications. Use when this capability is needed. |
| metadata | {"author":"davepoon"} |
Authentication Patterns in Next.js
Overview
Next.js supports multiple authentication strategies. This skill covers common patterns including NextAuth.js (Auth.js), middleware-based protection, and session management.
Authentication Libraries
| Library | Best For |
|---|
| NextAuth.js (Auth.js) | Full-featured auth with providers |
| Clerk | Managed auth service |
| Lucia | Lightweight, flexible auth |
| Supabase Auth | Supabase ecosystem |
| Custom JWT | Full control |
NextAuth.js v5 Setup
Installation
npm install next-auth@beta
Configuration
import NextAuth from 'next-auth'
import GitHub from 'next-auth/providers/github'
import Credentials from 'next-auth/providers/credentials'
export const { handlers, auth, signIn, signOut } = NextAuth({
providers: [
GitHub({
clientId: process.env.GITHUB_ID,
clientSecret: process.env.GITHUB_SECRET,
}),
Credentials({
credentials: {
email: { label: 'Email', type: 'email' },
password: { label: 'Password', type: 'password' },
},
authorize: async (credentials) => {
const user = await getUserByEmail(credentials.email)
if (!user || !verifyPassword(credentials.password, user.password)) {
return null
}
return user
},
}),
],
callbacks: {
authorized: async ({ auth }) => {
return !!auth
},
},
})
API Route Handler
import { handlers } from '@/auth'
export const { GET, POST } = handlers
Middleware Protection
export { auth as middleware } from '@/auth'
export const config = {
matcher: ['/dashboard/:path*', '/api/protected/:path*'],
}
Getting Session Data
In Server Components
import { auth } from '@/auth'
import { redirect } from 'next/navigation'
export default async function DashboardPage() {
const session = await auth()
if (!session) {
redirect('/login')
}
return (
<div>
<h1>Welcome, {session.user?.name}</h1>
</div>
)
}
In Client Components
'use client'
import { useSession } from 'next-auth/react'
export function UserMenu() {
const { data: session, status } = useSession()
if (status === 'loading') {
return <div>Loading...</div>
}
if (!session) {
return <SignInButton />
}
return (
<div>
<span>{session.user?.name}</span>
<SignOutButton />
</div>
)
}
Session Provider Setup
'use client'
import { SessionProvider } from 'next-auth/react'
export function Providers({ children }: { children: React.ReactNode }) {
return <SessionProvider>{children}</SessionProvider>
}
import { Providers } from './providers'
export default function RootLayout({ children }) {
return (
<html>
<body>
<Providers>{children}</Providers>
</body>
</html>
)
}
Sign In/Out Components
import { signIn, signOut } from '@/auth'
export function SignInButton() {
return (
<form
action={async () => {
'use server'
await signIn('github')
}}
>
<button type="submit">Sign in with GitHub</button>
</form>
)
}
export function SignOutButton() {
return (
<form
action={async () => {
'use server'
await signOut()
}}
>
<button type="submit">Sign out</button>
</form>
)
}
Middleware-Based Auth
Basic Pattern
import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'
const protectedRoutes = ['/dashboard', '/settings', '/api/protected']
const authRoutes = ['/login', '/signup']
export function middleware(request: NextRequest) {
const token = request.cookies.get('session')?.value
const { pathname } = request.nextUrl
if (authRoutes.some(route => pathname.startsWith(route))) {
if (token) {
return NextResponse.redirect(new URL('/dashboard', request.url))
}
return NextResponse.next()
}
if (protectedRoutes.some( => pathname.(route))) {
(!token) {
loginUrl = (, request.)
loginUrl..(, pathname)
.(loginUrl)
}
}
.()
}
config = {
: [],
}
With JWT Verification
import { NextResponse } from 'next/server'
import { jwtVerify } from 'jose'
const secret = new TextEncoder().encode(process.env.JWT_SECRET)
export async function middleware(request: NextRequest) {
const token = request.cookies.get('token')?.value
if (!token) {
return NextResponse.redirect(new URL('/login', request.url))
}
try {
const { payload } = await jwtVerify(token, secret)
return NextResponse.next()
} catch {
return NextResponse.redirect(new URL('/login', request.url))
}
}
Role-Based Access Control
Extending Session Types
import { DefaultSession } from 'next-auth'
declare module 'next-auth' {
interface Session {
user: {
role: 'user' | 'admin'
} & DefaultSession['user']
}
}
export const { handlers, auth } = NextAuth({
callbacks: {
session: ({ session, token }) => ({
...session,
user: {
...session.user,
role: token.role,
},
}),
jwt: ({ token, user }) => {
if (user) {
token.role = user.role
}
return token
},
},
})
Role-Based Component
import { auth } from '@/auth'
import { redirect } from 'next/navigation'
export async function AdminOnly({ children }: { children: React.ReactNode }) {
const session = await auth()
if (session?.user?.role !== 'admin') {
redirect('/unauthorized')
}
return <>{children}</>
}
export default async function AdminPage() {
return (
<AdminOnly>
<AdminDashboard />
</AdminOnly>
)
}
Session Storage Options
JWT (Stateless)
export const { auth } = NextAuth({
session: { strategy: 'jwt' },
})
Database Sessions
import { PrismaAdapter } from '@auth/prisma-adapter'
import { prisma } from '@/lib/prisma'
export const { auth } = NextAuth({
adapter: PrismaAdapter(prisma),
session: { strategy: 'database' },
})
Custom Login Page
'use client'
import { signIn } from 'next-auth/react'
import { useSearchParams } from 'next/navigation'
export default function LoginPage() {
const searchParams = useSearchParams()
const callbackUrl = searchParams.get('callbackUrl') || '/dashboard'
return (
<div className="flex flex-col gap-4">
<button
onClick={() => signIn('github', { callbackUrl })}
className="btn"
>
Sign in with GitHub
</button>
<button
onClick={() => signIn('google', { callbackUrl })}
className="btn"
>
Sign in with Google
</button>
</div>
)
}
Security Best Practices
- Use HTTPS in production
- Set secure cookie flags (HttpOnly, Secure, SameSite)
- Implement CSRF protection (built into NextAuth)
- Validate redirect URLs to prevent open redirects
- Use environment variables for secrets
- Implement rate limiting on auth endpoints
- Hash passwords with bcrypt or argon2
Resources
For detailed patterns, see:
references/middleware-auth.md - Advanced middleware patternsreferences/session-management.md - Session strategiesexamples/nextauth-setup.md - Complete NextAuth.js setup
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