Next.js 15 fully supports React 19, allowing developers to leverage its latest features, such as:

• React Compiler (Experimental) – Automates memoization to optimize performance.
• Improved server-side rendering and concurrent features.
• Enhanced debugging experience.

By integrating React 19, Next.js 15 ensures that applications remain up to date with the latest advancements in the React ecosystem. To learn more about React 19 and its impact on modern development, check out our React 19 article.

Example Usage of React Compiler

'use client';
import { useState } from 'react';

function Counter() {
  const [count, setCount] = useState(0);
  return  setCount(count + 1)}>Count: {count};
}

The React Compiler optimizes this component to reduce unnecessary re-renders automatically.

Turbopack, the new development bundler introduced by Vercel, is now stable in Next.js 15.

Benefits:

• Up to 76.7% faster local server startup.
• 96.3% faster code updates with Fast Refresh.
• Improved caching and incremental compilation.

To enable Turbopack in your project, use the following command:

next dev --turbo

This provides a significant speed boost for development workflows.

One of the most critical updates in Next.js 15 is its new caching defaults.

Key Changes:

• fetch() Requests and GET Route Handlers: Uncached by default (use cache: 'force-cache' to enable caching).
• Client Router Cache: Disabled by default for client-side navigation, ensuring fresh data.
• Better control over dynamic and static data fetching.

Next.js 15 introduces detailed hydration error messages, making debugging easier.

New Improvements:

• Clear error messages with source code highlights.
• Actionable suggestions to fix mismatches between server and client HTML.
• Better tooling support for React components.

These enhancements ensure a smoother development experience when dealing with hydration issues.

A new visual indicator now shows whether a route is static or dynamic during development.

• Helps developers optimize page performance.
• Quickly identifies rendering behavior for each route.

This feature is especially useful for performance optimization and debugging.

Next.js 15 introduces two exciting experimental features:

React Compiler

• Automatically optimizes React components without manual memoization.
• Reduces re-renders and improves app performance.

Partial Prerendering

• Allows prerendering of parts of a page.
• Improves loading speed while maintaining dynamic capabilities.

Using npm:

npm install next@latest react@rc react-dom@rc

Using yarn:

yarn add next@latest react@rc react-dom@rc

Also, refer to the Next.js 15 Upgrade Guide for breaking changes and migration steps.

Next.js 15 is packed with powerful improvements, making web development faster, smarter, and more efficient. From Turbopack’s stability to better caching controls, enhanced hydration debugging, and support for React 19, this release ensures a smoother development experience.

Upgrade to Next.js 15 today and take advantage of its cutting-edge features!
For more details, check out the official Next.js 15 blog.