How does the tech stack checker work?

It fetches the page's published HTML and inspects four signals: script URLs, inline script contents, meta and DOM markers, and the HTTP response headers and cookies. Each signal is matched against a table of known technology fingerprints.

Can it detect everything a site uses?

No, and it says so. The checker reads published HTML only, so tools loaded at runtime by a tag manager may not appear. When a tag manager is detected, the results flag that the list may be incomplete rather than implying it is exhaustive.

What do 'confirmed' and 'likely' mean?

Confirmed means an unambiguous signal was found, such as a Google Tag Manager container ID or a server header. Likely means only a heuristic marker matched, such as a DOM attribute that a framework usually leaves behind but which can occur by coincidence.

Is the tech stack checker free?

Yes. No account is required, and full results are shown without a signup wall.

Free tool · no signup

What is any site built with?

Enter a domain to see its frameworks, analytics and eventing tools, CMS, hosting and CDN — read straight from the site's published code.

vercel.com

Vercel · 3 technologies detected

Cached result

Confirmed — unambiguous signal Likely — heuristic marker only

Framework & libraries

Next.js

Analytics

Google Analytics 4

Audience MeasurementConversion Tracking

Hosting

Vercel

Security headers

5/6

✓ HSTS Forces HTTPS on future visits

✓ Content Security Policy Restricts what the page may load

✓ X-Frame-Options Blocks clickjacking via framing

✓ X-Content-Type-Options Stops MIME-type sniffing

✓ Referrer Policy Controls referrer leakage

— Permissions Policy Limits browser feature access

AI readiness

Strong

/ 100

Content structure 62

Schema, FAQ markup and answer-shaped passages

Schema depth 50

2 valuable types detected

AI crawler access 100

13/13 tracked crawlers allowed

Machine-readable index 100

llms.txt present

Not detected

— No tag manager detectedEvery new tag needs a developer and a deploy.

— No consent management detectedAnalytics and advertising cookies without consent are a GDPR exposure.

— No error tracking detectedFront-end exceptions reach users before anyone on the team hears about them.

Subdomains

assets.vercel.com go.vercel.com saml-authentication.vercel.com examples.vercel.com admin.vercel.com auth.vercel.com security.vercel.com info.vercel.com edge-config.vercel.com checkout.vercel.com pyra.vercel.com partners.vercel.com import.vercel.com data.vercel.com nextjs.examples.vercel.com links.vercel.com conf-feature-flags.vercel.com partners-classic.vercel.com image.ship.vercel.com hydrogen.examples.vercel.com upflow-email.billing.vercel.com servicedesk.vercel.com datarequest.vercel.com cdn1.vercel.com click.ship.vercel.com cdn2.vercel.com test.test0001.vercel.com view.ship.vercel.com edge-config-staging-3.vercel.com kms.vercel.com email.info.vercel.com cloud.ship.vercel.com customerio.vercel.com test.test0002.vercel.com test000002.vercel.com test0000001.vercel.com test.vertex.vercel.com qat-wxnext.vercel.com learning-portal.vercel.com www.learning-portal.vercel.com

From public certificate transparency logs. A name here has held a certificate; it may not currently serve a site.

This reads the site's published HTML only. It sees what the server sends, not what runs afterwards in a browser.

How does vercel.com actually perform in search?

Knowing the stack is one thing. Run a full audit to score the site for search and answer engines, and see every issue holding it back.

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