# Find what a site is built with

> Find a website’s framework, CMS or site builder, hosting and libraries from the traces in its code and headers, and learn what no checker can see.

Canonical page: https://sitepeel.dev/guides/what-is-a-website-built-with/

Look for the traces a stack leaves in the page: file paths, HTML attributes, generator tags and response headers. A free checker collects them with the evidence.

Published: 2026-10-24

Tool used in this guide: [CSS inspector & ruler](https://sitepeel.dev/css-inspector/index.md)

## How to use it

1. **Paste the link** Paste the site’s link into the free built-with checker. Sitepeel opens the page and lists what it finds.
2. **Check the evidence** Each result shows its evidence: a framework marker, a script or asset address, a response header or a CSS pattern.
3. **Or view the source** Press Ctrl+U (Cmd+Option+U on Mac) and search for _next, wp-content, data-wf or generator.
4. **Read the response headers** In DevTools, open Network, reload, select the first document request and read its response headers.

## Clues that name a framework or builder

Common traces in the page and what they usually mean

| Clue | Where to look | Usually means |
| --- | --- | --- |
| /_next/ in script paths | Page source, Network | Next.js |
| /_nuxt/ in script paths | Page source, Network | Nuxt |
| /_astro/ files, <astro-island> elements | Page source | Astro |
| ng-version attribute | Elements | Angular |
| data-v-… attributes | Elements | Vue |
| /wp-content/ and /wp-includes/ | Page source | WordPress |
| cdn.shopify.com files | Page source, Network | Shopify |
| data-wf-site and data-wf-page | Elements | Webflow |
| framerusercontent.com files | Network | Framer |
| static.wixstatic.com files | Network | Wix |
| <meta name="generator"> | Page source | The CMS or builder, unless removed |

## Clues in the response headers

Headers that hint at hosting and the server

| Header | Usually means |
| --- | --- |
| server: cloudflare, cf-ray | Cloudflare, often in front of another host |
| server: Vercel, x-vercel-id | Vercel |
| server: Netlify, x-nf-request-id | Netlify |
| server: GitHub.com | GitHub Pages |
| x-amz-cf-id | Amazon CloudFront |
| x-powered-by: Next.js, Express or PHP | The framework or server language, unless switched off |

## Libraries, styles, fonts and analytics

The checker also shows the fonts and colors, from the same measurements as the DESIGN.md generator.

- Tailwind CSS: utility classes such as flex, px-4, text-sm and md:grid-cols-3 all through the markup.
- Animation and 3D: GSAP, three.js, Lottie or Spline script files in the Network tab.
- Analytics: requests to googletagmanager.com, plausible.io or posthog.com, for example.
- Fonts: requests to fonts.googleapis.com or use.typekit.net (Adobe Fonts), or self-hosted .woff2 files.

- [Generate the full DESIGN.md free](https://sitepeel.dev/design-md/index.md)

## What no checker can see

Treat each result as evidence, not proof. Two independent clues, such as a file path and a header, are stronger than one.

- Back-end code, databases and APIs that stay on the server
- Traces the site removed, such as generator tags or x-powered-by headers
- Frameworks hidden by a custom build that renames their usual paths
- The real host behind a CDN or proxy

- [Check whether a site looks AI-generated](https://sitepeel.dev/guides/check-if-website-looks-ai-generated/index.md)

## Questions and answers

### How can I tell what CMS a website uses?

View the page source and look for a generator meta tag or telltale paths, such as /wp-content/ for WordPress or cdn.shopify.com for Shopify. Site builders like Webflow, Framer and Wix also load files from their own domains.

### How do I know if a site uses Next.js?

Look for script files under /_next/ in the page source or Network tab. An x-powered-by: Next.js response header confirms it, unless the site turned that header off.

### Can I see what database or back end a website uses?

Usually not. Databases, server code and APIs stay on the server. Headers such as x-powered-by sometimes name the server language or framework, but many sites remove them.

### Why is part of the stack missing from the results?

Server-side tools and code that never reaches the browser can’t be seen from outside, and some sites hide or rename their tools. A result only appears when there is a clear sign.

## Further reading

- [Next.js: the x-powered-by header (poweredByHeader)](https://nextjs.org/docs/app/api-reference/config/next-config-js/poweredByHeader)
- [Vercel: response headers](https://vercel.com/docs/headers/response-headers)
- [Cloudflare: HTTP headers](https://developers.cloudflare.com/fundamentals/reference/http-headers/)

## Related pages

- [Inspect a website design](https://sitepeel.dev/guides/how-to-inspect-website-design/index.md): Inspect a website’s layout, fonts, colors and spacing in Chrome, step by step, with a copyable checklist for recording what you find.
- [CSS inspector & ruler](https://sitepeel.dev/css-inspector/index.md): Inspect website dimensions, padding and margins. Measure spacing directly on the page with Sitepeel’s visual CSS inspector and ruler.
- [Extract a design reference](https://sitepeel.dev/guides/extract-website-design-system/index.md): Turn a website’s repeated colors, type, spacing and components into a design system reference in DESIGN.md, with an evidence template to copy.
- [Check if a site looks AI-made](https://sitepeel.dev/guides/check-if-website-looks-ai-generated/index.md): Spot the tells of AI-made web design, from default fonts and purple gradients to icon card grids, then check any site free and get a fix prompt.