Getting Started with Next.js 15: The Complete Guide

Next.js 15 brings significant improvements to the React development experience with enhanced performance, better developer experience, and powerful new features.

What's New in Next.js 15?

1. Enhanced App Router

The App Router has been refined with better type safety and improved performance:

// app/page.tsx
export default function HomePage() {
  return (
    <div>
      <h1>Welcome to Next.js 15!</h1>
      <p>Built with the latest React 19 features</p>
    </div>
  )
}

2. Server Components by Default

All components in the app directory are Server Components by default, providing:

• Zero JavaScript: Components render on the server
• Better Performance: Reduced bundle sizes
• SEO Benefits: Fully rendered HTML

3. Improved TypeScript Support

Better type inference and error messages:

// Automatic type inference for params
export default function Page({ params }: { params: { slug: string } }) {
  return <h1>Post: {params.slug}</h1>
}

Key Features

Streaming and Suspense

import { Suspense } from 'react'
 
export default function Page() {
  return (
    <Suspense fallback={<Loading />}>
      <ExpensiveComponent />
    </Suspense>
  )
}

Data Fetching

async function getData() {
  const res = await fetch('https://api.example.com/data')
  return res.json()
}
 
export default async function Page() {
  const data = await getData()
  return <main>{/* Render data */}</main>
}

Migration Tips

1. Start with App Router: New projects should use the App Router
2. Gradual Migration: Migrate pages incrementally
3. Update Dependencies: Ensure React 19 compatibility

Performance Benefits

• Up to 30% faster build times
• Reduced JavaScript bundle sizes
• Improved Core Web Vitals scores

Next.js 15 represents a major step forward in React development, making it easier to build fast, SEO-friendly applications with modern React patterns.