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

React is a JavaScript library for building user interfaces, focusing on UI components. Next.js is a framework built on top of React that adds server-side rendering, routing, and other features to build full web applications.

Quick Comparison

This table summarizes the main differences between Next.js and React.

Feature	React	Next.js
Type	UI library	Full framework built on React
Rendering	Client-side rendering by default	Supports server-side rendering, static site generation, and client-side rendering
Routing	Manual setup with libraries like React Router	Built-in file-based routing system
API Routes	Not included	Supports backend API routes within the app
Setup Complexity	Requires manual setup for routing and SSR	Zero-config setup for SSR and routing
Use Case	Building UI components	Building complete web applications with React

Key Differences

React is focused solely on building UI components. It handles how your app looks and behaves on the client side. You need to add other tools for routing, server-side rendering (SSR), or backend logic.

Next.js extends React by adding features like server-side rendering, static site generation, and a file-based routing system. This means you can build full web apps with pages, API endpoints, and optimized performance out of the box.

While React apps run mostly in the browser, Next.js apps can pre-render pages on the server, improving load speed and SEO. Next.js also simplifies routing by automatically creating routes from your files, unlike React where you must configure routes manually.

Code Comparison

Here is a simple React component that displays a greeting message.

javascript

import React from 'react';

export default function Greeting() {
  return <h1>Hello from React!</h1>;
}

Output

<h1>Hello from React!</h1>

Next.js Equivalent

The same greeting page in Next.js uses a file-based route and supports server-side rendering automatically.

javascript

export default function Greeting() {
  return <h1>Hello from Next.js!</h1>;
}

Output

<h1>Hello from Next.js!</h1>

When to Use Which

Choose React when you want to build UI components or single-page applications and prefer to control routing and rendering setup yourself.

Choose Next.js when you want a full framework that handles routing, server-side rendering, and static site generation with minimal setup, ideal for SEO-friendly and fast web apps.

Key Takeaways

React is a UI library; Next.js is a full framework built on React.

Next.js adds server-side rendering and automatic routing to React apps.

Use React for flexible UI components and Next.js for complete web apps.

Next.js improves SEO and performance with pre-rendering features.

Next.js simplifies setup with built-in routing and API routes.