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

React is a library for building user interfaces, focusing on components and client-side rendering. Next.js is a framework built on React that adds server-side rendering, routing, and other features to create full web applications easily.

Quick Comparison

Here is a quick side-by-side look at key aspects of Next.js and React.

Aspect	React	Next.js
Type	UI library	Full React framework
Rendering	Client-side only	Server-side & client-side
Routing	Manual setup needed	Built-in file-based routing
Setup	Flexible, manual	Opinionated, zero-config start
API Routes	No	Yes, built-in API support
Use Case	Single-page apps, UI components	Full web apps with SEO & performance

Key Differences

React is focused on building UI components and leaves routing, data fetching, and server rendering to the developer or other libraries. It runs mainly in the browser, so you build single-page applications where the page updates dynamically without full reloads.

Next.js extends React by adding server-side rendering (SSR) and static site generation (SSG), which help pages load faster and improve SEO. It also provides a built-in routing system based on your file structure, so you don't need to configure routes manually.

Next.js includes features like API routes to build backend endpoints inside the same project, automatic code splitting, and optimized performance defaults. React requires more setup and additional tools to achieve these features, making Next.js a more complete solution for full web apps.

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 implemented as a Next.js page with server-side rendering.

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 full control over your app setup, prefer client-side rendering, or are building UI components to integrate into other projects.

Choose Next.js when you want a ready-to-go framework with server-side rendering, automatic routing, and better SEO out of the box for full web applications.

Key Takeaways

React is a UI library focused on building components with client-side rendering.

Next.js is a React framework adding server-side rendering, routing, and backend features.

Next.js simplifies building full web apps with better SEO and performance by default.

Use React for flexible UI projects and Next.js for complete web applications.

Next.js includes built-in routing and API routes, reducing setup time.