Tech stack detector. 10 categories, 60+ tools.
Paste HTML source. We scan for JS framework, CSS framework, analytics, payment, ads, chat, CRM, A/B testing, CDN, tag manager signatures — 60+ tools across 10 categories. Browser-only, no upload.
Paste HTML source. We scan 60+ signatures across 10 categories — JS framework, CSS framework, analytics, marketing, payment, ads, chat, A/B testing, tag manager, CDN. Each match shows which signature triggered it, so you can verify rather than trust blindly.
How do I get HTML source?
- View source: right-click → 'View page source' (or Ctrl-U / Cmd-U). Select all, copy.
- curl:
curl -L https://example.comfor the raw HTML. - DevTools (best for SPAs + tag-manager-loaded tools): F12 → Elements → right-click document root → Copy → Copy outerHTML. The rendered DOM includes scripts loaded after page load.
Privacy: detection happens in your browser. Nothing is sent or logged.
Ten categories. 60+ specific tools.
JS framework + CSS framework. The foundation of how a page is built and styled. Detecting these tells you what the developer experience is — React + Tailwind sites are typically component-driven and have strong type discipline; legacy jQuery + Bootstrap sites are pattern-mature but harder to evolve. Identifying the framework helps scope a frontend rebuild or a takeover engagement.
Analytics + marketing + CRM. What data the site collects and where it sends it. The presence of Klaviyo on a Shopify site signals an email-marketing-led DTC playbook; HubSpot on a B2B site signals an inbound-sales motion. Useful both for competitive intelligence and for migration scoping (any data integration moving with the platform change).
Payment + ads. Revenue-side stack. Stripe is the modern default; PayPal + Apple Pay extend coverage. The ads / pixel set tells you the customer-acquisition channels — Meta Pixel + Google Ads + TikTok Pixel together is the modern DTC paid-acquisition stack.
Chat + A/B testing + tag manager. The growth-team layer. Intercom + Optimizely + GTM is a textbook B2B-SaaS growth stack; Crisp + VWO + GTM signals a more cost-conscious team. The tag manager presence specifically tells you whether the marketing team has independence from engineering for tracking changes.
CDN + hosting hints. Inferred from asset URLs in the HTML. Cloudflare, Vercel, Netlify, AWS CloudFront, Fastly all have characteristic asset-URL patterns. For confirmation, pair with our HTTP Headers Checker — CDN headers (cf-ray, x-vercel-id, x-served-by) are more authoritative than HTML signals.
Four jobs this tool covers.
Job 1: Sales prospecting. Targeting agencies that work on Shopify Plus + Klaviyo + Stripe stack? Pre-qualify prospects by detecting their stack from public HTML. Saves the discovery call from being a "what tools do you use" interrogation. Especially valuable for agency teams with a narrow ICP.
Job 2: Migration / takeover scoping. Inheriting a site as a new agency-of-record? Detect the full stack to know what integrations need preserving, what tracking pixels need re-installing on the new platform, what email tools need reconnecting. A Shopify site with 12 tools detected is a different scope than one with 3.
Job 3: Vendor / acquisition diligence. Knowing a target's stack tells you about their operating-cost profile (Optimizely is enterprise-priced, VWO is mid-market), their engineering velocity (custom tooling vs SaaS-stitched), and their replacement cost. Useful pre-diligence signal before the data room opens.
Job 4: Competitive intelligence. Knowing a competitor's analytics + ads + A/B testing stack reveals their measurement maturity. A competitor with PostHog + Mixpanel + Heap is investing heavily in product analytics; one with just GA4 isn't. Pair with our CMS Detector for the platform layer.
Six questions users ask.
How is this different from CMS Detector?
CMS Detector identifies the platform that builds the page — WordPress, Shopify, Webflow, Next.js. Tech Stack Detector identifies the tools layered on top — analytics, payment, A/B testing, chat widgets, CSS framework, etc. The two complement: CMS tells you the foundation, Tech Stack tells you what's bolted on. A WordPress site might have GA + Klaviyo + Stripe + Hotjar + Tailwind layered on top; a Next.js app might have Segment + PostHog + Stripe + Intercom + Tailwind. Different tools for the same job: knowing the full stack vs knowing the platform.
Which categories does it scan?
Ten categories. (1) JS framework — React, Vue, Angular, Svelte, Preact, Alpine, htmx. (2) CSS framework — Tailwind, Bootstrap, Bulma, Foundation. (3) Analytics — Google Analytics, Plausible, Fathom, Mixpanel, Heap, Segment, Amplitude, PostHog. (4) Marketing — HubSpot, Marketo, Pardot, Klaviyo, Mailchimp. (5) Payment — Stripe, PayPal, Klarna, Square. (6) Ads + tracking — Facebook Pixel, TikTok Pixel, LinkedIn Insight, AdSense. (7) Chat / support — Intercom, Drift, Crisp, Zendesk, Tawk.to. (8) A/B testing — Optimizely, VWO, AB Tasty. (9) Tag manager — Google Tag Manager, Adobe Launch. (10) CDN / hosting hints — Cloudflare, Vercel, Netlify, AWS.
How does the signature scan work?
Each tool has 1-3 signatures: a unique script src URL pattern (e.g. https://www.googletagmanager.com/gtag/js for GA4), a unique global JS variable (e.g. window.fbq for Facebook Pixel), or a characteristic class / data-attribute pattern (e.g. data-stripe for Stripe Elements). The scan runs all signatures against the input HTML and returns matches. Each match is reported with the matched pattern so you can see why we flagged it. Signatures are derived from each tool's official integration docs; we don't fingerprint via behavioral or runtime signals.
Why isn't tool X detected?
Three reasons. (1) The signature isn't in our pattern library — niche tools or recent launches may not be covered yet; check our hub for the next dev-tool batch. (2) The tool is loaded asynchronously via Tag Manager — the HTML you paste only shows the initial script tags, not what GTM injects after page load. To detect tools loaded via GTM, use the rendered DOM from DevTools. (3) The site has obfuscated or self-hosted the tool's script (e.g. proxying GA through a custom domain). Self-hosted tracking is increasingly common for privacy and ad-blocker resistance; signature-based detection misses it.
Can I trust 'Cloudflare detected' as confirmation of CDN?
Partially. The Cloudflare signature here looks for cf-* class patterns or comment markers in the HTML — these can appear if the site uses Cloudflare's challenge or analytics features. Cloudflare CDN detection is more reliably done via response headers (cf-ray, cf-cache-status) — see our HTTP Headers Checker for that. The HTML signature here is a hint, not a confirmation. Use both signals together for a confident answer.
Is the HTML I paste sent anywhere?
No. Detection happens entirely in your browser. The page is static HTML; the only network request is the initial page load. Safe for HTML from internal staging environments, partner integrations, or any source you don't want to share. We never see your input.
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