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Raj Aryan
Raj Aryan

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🔥 Most Asked Next.js Interview Questions (With Answers) – 2025 Edition

Next.js is one of the most in-demand frameworks in modern web development. If you're applying for roles at companies like Vercel, Shopify, PayPal, or any top startup, mastering these questions can give you an edge.

This post covers the most common and high-impact interview questions for Next.js, categorized by difficulty level. Plus, we’ve added code snippets, explanations, and real-world interview insights.

🚀 Why is Next.js So Popular in 2025?

  • ✅ Built on top of React
  • ✅ Supports Server-side Rendering (SSR)
  • ✅ Blazing fast Static Site Generation (SSG)
  • ✅ Powerful App Router with nested layouts and Server Components
  • ✅ First-class TypeScript support
  • ✅ SEO-friendly architecture

✅ Basic Next.js Interview Questions

1. What is Next.js?

Answer: Next.js is a full-stack React framework that provides SSR, SSG, and client-side routing. It enhances performance and SEO while simplifying development.

2. What is the difference between SSR, CSR, and SSG?

Type Render Time SEO Performance
SSR On each request Good Slower
CSR On client browser Poor Fast after load
SSG At build time Great Very fast

3. What are getStaticProps and getServerSideProps?

  • getStaticProps: Runs at build time. Used for SSG.
  • getServerSideProps: Runs on every request. Used for SSR. 
// SSG
export async function getStaticProps() {
  return { props: { message: "Hello" } };
}

// SSR
export async function getServerSideProps() {
  return { props: { message: "From server" } };
}
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4. What is ISR (Incremental Static Regeneration)?

ISR enables on-demand regeneration of pages.

export async function getStaticProps() {
  return {
    props: { data },
    revalidate: 10 // seconds
  }
}
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5. What are API Routes in Next.js?

You can create backend APIs using files inside /pages/api/.

// pages/api/hello.js
export default function handler(req, res) {
  res.status(200).json({ msg: 'Hello world!' });
}
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⚙️ Intermediate Questions

6. What is Middleware in Next.js?

Middleware lets you intercept requests and perform operations like redirects or auth checks before the request is handled.

// middleware.ts
import { NextResponse } from 'next/server';
export function middleware(request) {
  return NextResponse.next();
}
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7. What is the App Router?

Introduced in Next.js 13+, it uses a new app/ directory to support:

  • Nested layouts
  • Server Components
  • Streaming
  • Loading states

8. How does Next.js handle images?

With the next/image component:

  • Automatic resizing
  • Lazy loading
  • Optimized formats (like WebP)

9. How do you implement dynamic routes?

Use brackets to denote dynamic segments:

// pages/blog/[slug].js
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URL: /blog/my-first-post

10. How does Next.js support SEO?

  • Pre-rendering (SSR & SSG)
  • <Head> component for meta tags
  • OpenGraph support for social sharing

🧠 Advanced Questions Asked by Top Companies

11. How do you handle authentication?

  • Use next-auth, JWTs, or Clerk
  • Use getServerSideProps to verify tokens
  • Use middleware to block routes

12. What are Server Components?

Server Components:

  • Run on the server
  • Reduce JS bundle size
  • Cannot use browser-only hooks (like useEffect)

13. What is a Layout in App Router?

Defined in app/layout.tsx, layouts let you wrap pages and persist components like navbars and footers across routes.

export default function Layout({ children }) {
  return (
    <div>
      <Navbar />
      {children}
    </div>
  )
}
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14. How can you optimize a Next.js application?

  • Use SSG whenever possible
  • Enable ISR
  • Optimize images
  • Defer scripts
  • Split code using dynamic imports
  • Use caching headers

📦 GitHub Boilerplate Starter

Looking for a real-world template to practice?
Check out Vercel’s Next.js boilerplate examples

🏁 Final Thoughts

Mastering Next.js isn’t just about knowing the syntax — it’s about understanding when and why to use its powerful features.

🧠 Want to ace your interview? Start with these and build real projects using SSR, SSG, and the App Router!

🙌 If you found this helpful, don’t forget to:

✅ Save this post
✅ Share with a fellow dev
✅ Follow me for more frontend interview prep!

#NextJS #JavaScript #React #InterviewPrep #Frontend #WebDev #FullStack #DevInterview #Hiring #2025

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