Next.js Page Router vs App Router

Next.js gives us two ways of building apps: the older Page Router (/pages) and the newer App Router (/app).
Here’s the difference explained simply:

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The Simple Idea

• Page Router (old way):
  You put files inside /pages. Each file = one route. It’s simple, but limited when your app grows.
• App Router (new way):
  You put files inside /app. It uses React Server Components, layouts, and modern features. It’s more powerful, but needs a bit more learning.

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Analogy 🪟

Think of it like building a house:

• Page Router = separate rooms. Each room (page) has its own door. If you want a shared wall (like a layout), you must rebuild it in every room.
• App Router = house with shared walls. Rooms (pages) can share layouts, data fetching, and logic without repeating work.

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Key Differences 🔑

• File location: /pages vs /app
• Rendering: Page Router = fully client-side components; App Router = supports Server Components
• Layouts: Page Router = no built-in layouts; App Router = nested layouts by default
• Data fetching: Page Router = getServerSideProps / getStaticProps; App Router = async functions inside components (simpler & more flexible)
• Best for:
  • Page Router → quick prototypes, small apps
  • App Router → modern apps, scalable projects, production-ready

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Code Example

Page Router

// pages/about.tsx
export default function About() {
  return <h1>About Page</h1>;
}

App Router

// app/about/page.tsx
export default function About() {
  return <h1>About Page</h1>;
}

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When to Use?

• ✅ New project → App Router (future of Next.js)
• ✅ Old project already using /pages → stay with Page Router unless you want to migrate
• ❌ Don’t mix them in the same route (but you can run both in one project during migration)

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That’s it! 🎉