Introduction

Next.js has become one of the most popular frameworks for building modern web applications due to its performance, scalability, and ease of use. Whether you are a frontend developer, full-stack engineer, or UIUX specialist, mastering Next.js can significantly enhance your career opportunities. This article covers a comprehensive list of Next.js interview questions along with detailed answers to help you prepare for your Next.js interview. We will cover beginner to advanced-level Next.js interview questions for experienced professionals to ensure a thorough understanding of the framework.

Basic Next.js Interview Questions

1. What is Next.js, and why is it used?

Next.js is a React-based framework that enables server-side rendering (SSR) and static site generation (SSG). It is widely used for building fast, scalable, and SEO-friendly web applications.

Key Features:

• Hybrid rendering (SSR & SSG)
• Automatic code splitting
• API routes
• Optimized performance and SEO
• Built-in support for CSS and image optimization

2. How does Next.js differ from React.js?

3. What are the different rendering methods in Next.js?

Next.js supports multiple rendering techniques:

• Server-Side Rendering (SSR) – Content is generated on each request.
• Static Site Generation (SSG) – Content is pre-rendered at build time.
• Client-Side Rendering (CSR) – Content is generated in the browser.
• Incremental Static Regeneration (ISR) – Updates static content without rebuilding the entire site.

Intermediate Next.js Interview Questions

4. Explain file-based routing in Next.js.

Unlike React, which requires external libraries like React Router, Next.js uses a file-based routing system. The files inside the pages/ directory automatically become routes.

Example:

// pages/index.js
export default function Home() {
  return 
Welcome to Next.js!
;
}

The above code will be accessible at / (home route).

5. What is API Routing in Next.js?

Next.js provides built-in API routes inside the pages/api/ directory, allowing developers to create backend endpoints.

Example:

// pages/api/hello.js
export default function handler(req, res) {
  res.status(200).json({ message: "Hello, world!" });
}

This API can be accessed at http://localhost:3000/api/hello.

6. What is Image Optimization in Next.js?

Next.js provides the next/image component for automatic image optimization, reducing load time, and improving performance.

Example:

import Image from 'next/image';
export default function Profile() {
  return ;
}

Advanced Next.js Interview Questions for Experienced Professionals

7. What is Incremental Static Regeneration (ISR)?

ISR allows you to update static content without rebuilding the entire application. This is useful for sites that need frequent updates.

Example:

export async function getStaticProps() {
  return {
    props: { time: new Date().toISOString() },
    revalidate: 10, // Revalidate every 10 seconds
  };
}

8. How do you implement middleware in Next.js?

Middleware in Next.js is used for handling requests before they reach a route.

Example:

// middleware.ts
import { NextResponse } from 'next/server';
export function middleware(req) {
  if (!req.cookies.auth) {
    return NextResponse.redirect('/login');
  }
}

9. Explain Dynamic Routing in Next.js.

Next.js allows dynamic routing using bracket notation in filenames.

Example:

// pages/post/[id].js
import { useRouter } from 'next/router';
export default function Post() {
  const router = useRouter();
  return 
Post ID: {router.query.id}
;
}

This route will dynamically handle URLs like /post/123.

10. What are some Next.js best practices?

• Use getServerSideProps for frequently changing data.
• Prefer getStaticProps for static content.
• Optimize images using next/image.
• Implement caching strategies for better performance.
• Use middleware for authentication and authorization.

Conclusion

Preparing for a Next.js interview requires understanding its core concepts, features, and best practices. This article covered Next.js interview questions and answers, ranging from basic to advanced topics. Whether you’re a beginner or an experienced developer, these Next.js interview questions for experienced professionals will help you confidently tackle any Next.js interview.