How to Tell if a Website Uses Next.js (2026 Guide)

What Is Next.js?

Next.js is an open-source React framework created and maintained by Vercel. It extends React with built-in support for server-side rendering (SSR), static site generation (SSG), incremental static regeneration (ISR), API routes, and image optimisation—features that would otherwise require significant custom configuration.

As of 2026, Next.js is one of the most starred JavaScript repositories on GitHub and is used by companies including Vercel, TikTok, Twitch, Notion, and thousands of SaaS and e-commerce businesses. Its App Router architecture, introduced in Next.js 13 and matured in subsequent versions, enables React Server Components and streaming rendering.

Why Detect Next.js?

Knowing that a website is built with Next.js is useful across many professional contexts:

• Developers and agencies: Identify potential clients or partners who already use Next.js for consulting, optimisation, or migration engagements.
• Competitive research: Understand the engineering maturity and infrastructure choices of a competitor.
• SaaS sales: Next.js is commonly used by growth-stage and enterprise SaaS companies—identifying it can help qualify prospects.
• Recruiters: Companies using Next.js often have strong frontend engineering teams and are actively hiring React developers.
• Security researchers: Identify Next.js deployments to assess whether they are running outdated versions with known vulnerabilities.

Fastest Method: Free Scanner Tool

The quickest and most reliable way to detect Next.js is to use Web Reveal—a free technology scanner that performs live analysis of any URL and returns a full technology stack breakdown, including the JavaScript framework, hosting provider, CDN, and analytics tools in use.

Enter the website URL on the Web Reveal homepage. Within seconds, results will confirm whether the site uses Next.js, the version where detectable, and additional context about the full stack.

The Web Reveal Chrome extension detects Next.js automatically as you browse, displaying the result in the browser toolbar without requiring you to visit the Web Reveal site.

X-Powered-By HTTP Header

By default, Next.js adds an HTTP response header to every page:

X-Powered-By: Next.js

To check for this header, open browser developer tools (F12), go to the Network tab, reload the page, select the main HTML document request, and inspect the Response Headers. If X-Powered-By: Next.js is present, the site uses Next.js.

Note: This header can be disabled by setting poweredByHeader: false in next.config.js. Many production sites disable it for security reasons. Use the signals below as fallbacks.

__NEXT_DATA__ Script Tag

One of the most reliable manual indicators of Next.js is the __NEXT_DATA__ inline script tag present in the HTML of pages rendered with Next.js's Pages Router. Press Ctrl+U to view the page source and search for __NEXT_DATA__. If found, the page is rendered by Next.js.

This script contains a JSON object with the page's props, build ID, and runtime configuration:

<script id="__NEXT_DATA__" type="application/json">{"props":{...},"buildId":"..."}</script>

The buildId value inside this object is a unique identifier for each Next.js build, which can also be used to confirm the framework.

Note: Sites using Next.js 13+ App Router without any Pages Router pages may not include __NEXT_DATA__. Look for the other signals below in those cases.

/_next/static/ Asset Paths

Next.js outputs all compiled JavaScript chunks, CSS files, and static assets to a directory called /_next/static/. These files are served directly by the Next.js server or a CDN. Look in the page source for script and link tags referencing paths like:

• /_next/static/chunks/ — JavaScript module chunks
• /_next/static/css/ — Compiled CSS stylesheets
• /_next/static/media/ — Optimised static media files
• /_next/image?url=... — Next.js's built-in image optimisation endpoint

Searching the page source for /_next/ is one of the simplest and most reliable manual checks for Next.js. This path is hard-coded into the framework's build output and cannot easily be changed.

JavaScript Globals and React Markers

Next.js builds on React, so both Next.js and React fingerprints are present in the browser environment. Open the browser console (F12 → Console) and check for:

• window.__NEXT_DATA__ — Set by Next.js on page load to expose page data to the client.
• window.next — The Next.js client-side router and runtime object.
• window.__NEXT_P — Next.js prefetch queue array.
• React DevTools detection: React sets window.__REACT_DEVTOOLS_GLOBAL_HOOK__, which is a secondary indicator that the page uses React (and potentially Next.js).

Typing window.next in the browser console and receiving a non-undefined object strongly indicates a Next.js application.

Vercel Deployment Indicators

A large proportion of Next.js sites are deployed on Vercel, the company that created Next.js. Vercel deployments often include additional identifying signals:

• x-vercel-id HTTP response header — Unique Vercel request identifier.
• x-vercel-cache HTTP response header — Indicates Vercel's edge cache status.
• DNS pointing to cname.vercel-dns.com or Vercel's edge network IP ranges.
• Preview deployment URLs at [project-name]-[hash].vercel.app.

While a Vercel deployment does not guarantee Next.js (other frameworks can be deployed to Vercel), the combination of Vercel hosting and Next.js signals is a very strong indicator.

How Web Reveal Detects Next.js

Web Reveal performs live HTTP analysis of the target URL and checks for multiple Next.js fingerprints simultaneously:

• The X-Powered-By: Next.js HTTP response header
• Presence of __NEXT_DATA__ in the HTML source
• Script and link tags referencing /_next/static/ paths
• The window.next and window.__NEXT_DATA__ JavaScript globals
• Vercel deployment headers and DNS indicators where present

Because Web Reveal cross-references multiple signals, it can confirm Next.js even when the X-Powered-By header has been disabled or when the site uses a custom domain and CDN that obscures the hosting provider.

Frequently Asked Questions

How can I tell if a website uses Next.js?

The fastest method is to scan the URL with Web Reveal. Manually, check the HTTP response headers for X-Powered-By: Next.js, look for __NEXT_DATA__ in the page source, or search for /_next/static/ in script URLs.

What is Next.js and why is it popular?

Next.js is a React-based web framework that adds server-side rendering, static site generation, API routes, and production-ready optimisations to React. It is popular because it dramatically reduces the configuration needed to build fast, SEO-friendly React applications, and it is backed by Vercel with a large open-source community.

Can a Next.js site hide that it uses Next.js?

Partially. The X-Powered-By header can be disabled in configuration. However, the /__next/static/ asset paths, __NEXT_DATA__ JSON tag, and React hydration markers are very difficult to fully remove from the production build output without custom post-processing.

Is Next.js the same as React?

No. React is a JavaScript UI library. Next.js is a full-stack framework built on React that adds routing, server-side rendering, API routes, and image optimisation. All Next.js sites use React, but not all React sites use Next.js—alternatives include Remix, Gatsby, Vite, and plain Create React App.