React vs Next.js: Key Differences and When to Use Each

React is a library for building user interfaces focusing on components, while Next.js is a framework built on React that adds routing, server-side rendering, and other features for full web apps. Use React for flexible UI building and Next.js when you want ready-made tools for SEO, routing, and performance.

Quick Comparison

Here is a quick side-by-side look at React and Next.js on key factors.

Factor	React	Next.js
Type	UI library	Full React framework
Rendering	Client-side only by default	Supports server-side, static, and client-side rendering
Routing	Manual setup needed	Built-in file-based routing
Setup	Minimal, flexible	Opinionated with conventions
SEO	Needs extra setup	Optimized out of the box
Use Case	Custom UI components	Complete web apps with routing and SSR

Key Differences

React is a flexible library focused on building UI components. It handles how your app looks and behaves on the client side but does not include routing or server rendering by default. You need to add libraries like React Router for navigation and tools like Next.js or Gatsby for server-side rendering.

Next.js is a framework built on top of React that adds many features out of the box. It provides automatic routing based on your file structure, supports server-side rendering (SSR) and static site generation (SSG) for better SEO and performance, and includes API routes for backend logic. This makes Next.js a more complete solution for building full web applications.

In short, React gives you the building blocks, while Next.js gives you a ready-made structure and tools to build production-ready apps faster.

Code Comparison

This React example shows a simple component with client-side routing using React Router.

javascript

import React from 'react';
import { BrowserRouter as Router, Routes, Route, Link } from 'react-router-dom';

function Home() {
  return <h2>Home Page</h2>;
}

function About() {
  return <h2>About Page</h2>;
}

export default function App() {
  return (
    <Router>
      <nav>
        <Link to="/">Home</Link> | <Link to="/about">About</Link>
      </nav>
      <Routes>
        <Route path="/" element={<Home />} />
        <Route path="/about" element={<About />} />
      </Routes>
    </Router>
  );
}

Output

A page with navigation links 'Home' and 'About'. Clicking links changes the displayed heading between 'Home Page' and 'About Page' without reloading.

Next.js Equivalent

This Next.js example uses file-based routing with two pages automatically handled by the framework.

javascript

// pages/index.js
export default function Home() {
  return <h2>Home Page</h2>;
}

// pages/about.js
export default function About() {
  return <h2>About Page</h2>;
}

Output

Visiting '/' shows 'Home Page'. Visiting '/about' shows 'About Page'. Navigation is automatic based on URL with no extra setup.

When to Use Which

Choose React when you want full control over your app's structure, prefer to add only the features you need, or are building a single-page app without server-side rendering.

Choose Next.js when you want a fast setup with built-in routing, server-side rendering, and SEO benefits, especially for multi-page websites or apps that need good performance and discoverability.

Key Takeaways

React is a UI library; Next.js is a full React framework with routing and SSR.

Next.js simplifies routing and SEO with built-in features.

Use React for flexible UI-only projects and Next.js for complete web apps.

Next.js supports server-side rendering and static generation out of the box.

React requires extra setup for routing and SEO compared to Next.js.