Next.js 15 and the App Router: A Complete Migration Guide

Why Migrate to App Router?

Next.js 15 with the App Router represents a fundamental shift in how we build React applications, offering improved performance, simplified data fetching, and better developer experience.

Key Benefits

• React Server Components: Reduce client-side JavaScript
• Streaming: Progressive page rendering
• Simplified Data Fetching: No more getServerSideProps
• Improved Caching: Built-in request memoization
• Parallel Routes: Complex layouts made simple

Migration Steps

1. Audit Your App: Identify pages and API routes
2. Set Up App Directory: Create parallel structure
3. Convert Layouts: Create layout.tsx files
4. Migrate Pages: Convert to Server Components
5. Update Data Fetching: Replace getServerSideProps with async components
6. Handle Client Interactivity: Add 'use client' where needed

Next.js 15 New Features

• Turbopack for development (stable)
• Partial Prerendering (experimental)
• Improved TypeScript support
• Enhanced security headers