auth-patterns

# 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 ```bash npm install next-auth@beta ``` ### Configuration ```tsx // auth.ts 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 ```tsx // app/api/auth/[....