Nextjs Authentication

This is a comprehensive reference for implementing Auth.js 5 (NextAuth.js) authentication in Next.js 15+ App Router apps. It covers the full setup from installing dependencies and configuring OAuth providers to protecting routes with middleware, securing Server Actions, and implementing role-based access control. You'd reach for this when wiring up GitHub or Google sign-in, protecting dashboard routes, or ensuring your Server Components and Actions actually check authentication before exposing data. The patterns are solid and production-focused, with proper TypeScript types and clear examples of common scenarios like protected dashboards and admin panels. It assumes you're comfortable with App Router conventions but need the Auth.js specifics spelled out.

skills.sh installs: 3.9K
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last updated: Aug 21, 2026

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Install

$ npx -y skills add giuseppe-trisciuoglio/developer-kit --skill nextjs-authentication --agent claude-code

Installs into .claude/skills of the current project.

Files

Next.js Authentication

Overview

Provides authentication implementation patterns for Next.js 15+ App Router using Auth.js 5 (NextAuth.js), covering the complete authentication lifecycle from initial setup to production-ready role-based access control implementations.

When to Use

Setting up Auth.js 5 from scratch or adding OAuth providers
Implementing protected routes with Middleware
Handling authentication in Server Components and Server Actions
Implementing role-based access control (RBAC)
Creating credential-based or OAuth sign-in/sign-out flows

Instructions

1. Install Dependencies

Install Auth.js v5 (beta) for Next.js App Router:

npm install next-auth@beta

2. Configure Environment Variables

Create .env.local with required variables:

# Required for Auth.js
AUTH_SECRET="your-secret-key-here"
AUTH_URL="http://localhost:3000"

# OAuth Providers (add as needed)
GITHUB_ID="your-github-client-id"
GITHUB_SECRET="your-github-client-secret"
GOOGLE_CLIENT_ID="your-google-client-id"
GOOGLE_CLIENT_SECRET="your-google-client-secret"

Generate AUTH_SECRET with: