Next.js 15: What's New and Revolutionary

React 19 Support - The Foundation

Next.js 15 is built on React 19, bringing all the latest React features to your Next.js applications. React 19 introduces the React Compiler, Actions, improved hydration, and better error handling. These features work seamlessly with Next.js to provide an unparalleled development experience.

Async Request APIs - Game Changer

One of the most significant changes in Next.js 15 is the introduction of async request APIs. Headers, cookies, and params are now accessed asynchronously, aligning with React's async model and enabling better streaming and performance. While this requires some migration work, it unlocks powerful new capabilities.

import { headers, cookies } from 'next/headers';

export default async function Page() {
  // Access headers asynchronously
  const headersList = await headers();
  const userAgent = headersList.get('user-agent');
  
  // Access cookies asynchronously  
  const cookieStore = await cookies();
  const theme = cookieStore.get('theme');
  
  return <div>User Agent: {userAgent}</div>;
}

This async approach enables Next.js to optimize data fetching and rendering, reducing time to first byte and improving overall performance. The framework can now stream responses more efficiently, providing a better user experience especially on slower connections.

Smarter Caching Strategy

Next.js 15 introduces a more intuitive caching system. By default, fetch requests are no longer cached automatically - giving you explicit control over when and how data is cached. This prevents unexpected stale data issues and makes the caching behavior more predictable.

// Cached fetch request
const data = await fetch('https://api.example.com/data', {
  cache: 'force-cache', // Explicit caching
  next: { revalidate: 3600 } // Revalidate every hour
});

// No cache (default in Next.js 15)
const liveData = await fetch('https://api.example.com/live', {
  cache: 'no-store' // Always fresh
});

Turbopack Dev - Production Ready

Turbopack, the Rust-powered successor to Webpack, is now stable for development in Next.js 15. It delivers dramatically faster builds and hot module replacement (HMR), making your development experience significantly smoother. Early benchmarks show 10x faster updates compared to Webpack in large applications.

Major New Features

module.exports = {
  async headers() {
    return [
      {
        source: '/:path*',
        headers: [
          {
            key: 'X-Frame-Options',
            value: 'DENY',
          },
          {
            key: 'X-Content-Type-Options',
            value: 'nosniff',
          },
        ],
      },
    ];
  },
};

Breaking Changes & Migration

Next.js 15 includes some breaking changes, primarily around the async request APIs. Here's what you need to know to migrate your existing applications smoothly.

Performance Enhancements

Beyond the headline features, Next.js 15 includes numerous performance improvements across the board. From faster builds to optimized runtime performance, every aspect of the framework has been refined for production use at scale.

How to Upgrade

Upgrading to Next.js 15 is straightforward, but requires attention to the breaking changes. Follow this step-by-step guide to ensure a smooth migration from Next.js 14 to 15.

npm install next@latest react@latest react-dom@latest
# or
yarn add next@latest react@latest react-dom@latest
# or  
pnpm add next@latest react@latest react-dom@latest