What Is Next.js and Why Do Developers Love It?

The React Framework That Changed How Modern Websites Are Built

If you've been anywhere near web development conversations in the last five years, you've heard about Next.js. It's become the dominant way to build React-based web applications and websites, used by companies ranging from scrappy startups to some of the largest websites in the world. TikTok, Netflix, Hulu, Twitch, and thousands of other high-traffic sites run on Next.js.

For non-developers trying to understand what their development team is building or choosing, and for developers deciding whether Next.js is right for their next project, this guide explains what Next.js actually is, what problems it solves, and when it makes sense to use it.

What Next.js Is

Next.js is an open-source web development framework built on top of React, created and maintained by Vercel. It extends React's capabilities with features that are essential for production-ready websites but aren't included in React itself: routing, server-side rendering, static site generation, API routes, image optimization, and performance tooling.

Understanding this requires understanding the React context: React is a JavaScript library for building user interfaces. It's excellent at what it does — creating interactive UI components that update efficiently when data changes. But React alone is a library, not a complete framework. It doesn't include routing (navigating between pages), server-side rendering, or most of the infrastructure needed for a complete, production-ready website. Developers historically had to assemble these pieces themselves or use other tools.

Next.js solves this by providing all of those missing pieces in an integrated, opinionated framework that handles the infrastructure while the developer focuses on building features.

The Key Features That Make Next.js Powerful

Multiple Rendering Modes

The feature that most distinguishes Next.js from plain React: the ability to choose how each page is rendered.

Static Site Generation (SSG): Pages are pre-built as static HTML at build time. When a visitor requests the page, the pre-built HTML is served instantly — no server computation on each request. Blazingly fast, excellent for pages whose content doesn't change frequently (marketing pages, blog posts, documentation).

Server-Side Rendering (SSR): Pages are built on the server for each request. The server fetches any needed data and generates the HTML, which is sent to the browser. Slightly slower than static but serves fresh data on every request — appropriate for pages with user-specific content or frequently changing data.

Incremental Static Regeneration (ISR): A hybrid approach — pages are statically generated but can be regenerated at specified intervals or on-demand when content changes. Gets most of the speed benefits of static generation with the freshness of server rendering. Extremely useful for content-heavy sites that update regularly (news sites, e-commerce).

Client-Side Rendering: Some components render entirely in the browser, like traditional React. Used for highly interactive sections where SEO doesn't matter (dashboards, app interfaces).

This flexibility — being able to choose the right rendering strategy for each page — is one of the most powerful aspects of Next.js. A single application can serve the marketing homepage as static HTML (instant load, perfect SEO) while the user dashboard renders dynamically with the user's specific data.

File-Based Routing

Next.js uses the file system as the routing system. Create a file at pages/about.js and the route /about is automatically created. Create pages/blog/[slug].js and dynamic routes like /blog/my-article-title are handled. No routing configuration required — the file structure is the route structure.

This convention-over-configuration approach significantly reduces setup overhead and makes the project structure immediately understandable to any Next.js developer joining a project.

API Routes

Next.js can serve as its own backend API within the same project. Files in the /api directory become API endpoints — serverless functions that run on the server. This enables form handling, database queries, third-party API calls with hidden credentials, and any other server-side operations without a separate backend service.

For many web applications, this eliminates the need to build and maintain a separate backend — the Next.js application handles both the frontend rendering and the API layer.

Image Optimization

The <Image> component in Next.js automatically handles image optimization: resizing images to the optimal size for each device, converting to modern formats (WebP, AVIF), lazy loading below-fold images, and serving images from a CDN. What used to require significant configuration work is built-in and automatic.

Vercel Deployment Integration

Next.js is made by Vercel, and deploying Next.js applications to Vercel is nearly frictionless. Connect a GitHub repository, Vercel automatically detects Next.js, and every push to the main branch triggers a deployment. Preview deployments for every pull request allow reviewing changes before merging. The deployment experience is among the best in the industry.

Why Developers Love It: The Technical Appreciation

Developer experience: Next.js has invested heavily in making the development experience fast and pleasant. Fast Refresh shows code changes in the browser instantly without losing application state. Clear error messages with code frames pointing directly to the problem. TypeScript support built-in. The tools just work.

Performance defaults: Next.js makes it easy to build fast by default. Code splitting (only loading the JavaScript needed for each page), automatic image optimization, font optimization, and script loading controls are built into the framework. Achieving good Core Web Vitals is significantly easier in Next.js than in a generic React setup.

The App Router: Next.js 13+ introduced the App Router — a new routing paradigm built on React Server Components that enables server-side rendering at the component level (not just page level), streaming HTML for faster perceived load times, and more granular control over what runs on the server vs. client. It's a significant architecture evolution that makes complex applications more performant.

Large ecosystem: Next.js is enormously popular, which means extensive documentation, community answers to nearly any question, compatible libraries, and tooling support. The knowledge investment in learning Next.js pays forward across many projects because the skill is widely applicable.

When Next.js Is the Right Choice

Content-heavy websites with SEO requirements: Blogs, news sites, e-commerce, documentation. The static generation and SSR capabilities deliver excellent SEO because search engines receive fully-rendered HTML (not blank pages waiting for JavaScript to populate content).

Large or complex React applications: When a React application grows large enough that routing, code splitting, and performance optimization become significant concerns, Next.js provides the structure to handle these concerns systematically.

Applications that need both a frontend and a simple API: The API routes feature eliminates the need for a separate backend service for many use cases.

Teams already using React: Next.js is a natural extension of React knowledge — the same component model, the same hooks, the same ecosystem. The learning curve is adding framework-specific features on top of existing React skills.

When Next.js Is NOT the Right Choice

Simple marketing websites without complex interactivity: A 10-page business website doesn't need the infrastructure that Next.js provides. Webflow, Squarespace, or even a basic HTML/CSS/JavaScript implementation is simpler, faster to build, and easier to maintain for non-developers.

Teams without JavaScript/React expertise: Next.js requires JavaScript and React knowledge. For teams without these skills, the learning curve to Next.js is substantial. Using a CMS platform (Webflow, WordPress) is a more appropriate choice.

Projects where non-developer content management is important: Content in Next.js lives in code repositories or headless CMS APIs — not in a visual CMS interface. If marketing teams need to update content without developer involvement, a visual CMS (Webflow, WordPress with Gutenberg, Contentful with a UI) is more appropriate than Next.js.

The Bottom Line

Next.js is a mature, powerful, and increasingly dominant framework for building modern web applications and content sites with React. Its flexible rendering modes, developer experience, and performance defaults have made it the go-to choice for serious web applications. Its popularity and Vercel's investment in its development ensure it will remain a central part of the modern web development ecosystem.

For technical teams building complex, content-rich, or interactive web products, Next.js is often the right answer. For simpler marketing websites or teams without JavaScript expertise, the overhead isn't justified by the benefits — there are better tools for those use cases.

At Scalify, we select the right platform for each project's requirements — whether that's Webflow for marketing sites that need visual polish and fast delivery, or Next.js for applications with more complex technical requirements.