Say you have a list of 500 company websites and you want to know which run WordPress, which are on Shopify, who uses Cloudflare or Google Tag Manager. That's a typical prospecting, competitor-research or migration-audit question. Services like BuiltWith are great but priced for heavier use. For a quick, coarse pass, a single HTTP request per site gets you surprisingly far.

This post walks through doing that with an Apify actor I built, Website Tech Stack Detector. Disclosure: it's my actor and I earn a little when it's used.

How it works

For each URL it makes one plain HTTP request (no browser, no JavaScript execution), follows up to 5 redirects, and looks at:

  • response headers (server, cf-ray, x-vercel-id, ...)
  • <meta name="generator">
  • script URLs and a few well-known HTML markers (__NEXT_DATA__, /wp-content/)
  • cookie names (values are never read or stored)

About 60 technologies are recognised: CMS (WordPress, Drupal, Wix...), ecommerce (Shopify, WooCommerce, Magento...), analytics/tag managers, CDN/hosting, web servers, JS frameworks. Every detection includes the evidence that triggered it, so you can judge it yourself. It respects robots.txt by default.

Price

Pay-per-event: $0.005 per URL analyzed (at time of writing), so 500 sites is about $2.50. You're only charged for URLs fetched successfully (HTTP below 400). Timeouts, DNS failures, 4xx/5xx, non-public URLs and robots.txt skips are free. Compute is included.

Input 

{ "urls": [ { "url": "https://wordpress.org" }, { "url": "https://nextjs.org" }, { "url": "https://www.drupal.org" }, { "url": "example.com" } ], "respectRobotsTxt": true, "maxConcurrency": 5, "timeoutSecs": 20 }

Bare domains are accepted. For 500 sites, paste or generate the urls array from your spreadsheet; maxConcurrency goes up to 20.

Real output

I ran the actor's source locally on 10 URLs: 8 analyzed, 2 not analyzed and not charged (a 404 page and http://127.0.0.1, which is rejected as non-public). Two of the results:

[ { "input": "https://nextjs.org", "finalUrl": "https://nextjs.org", "httpStatus": 200, "technologies": [ { "name": "Vercel", "category": "Hosting", "evidence": "header x-vercel-id" }, { "name": "Next.js", "category": "JS framework", "evidence": "script src /\\/_next\\/static\\//" } ], "capturedAt": "2026-10-16T05:53:25.120Z" }, { "input": "https://www.drupal.org", "finalUrl": "https://new.drupal.org/", "httpStatus": 200, "technologies": [ { "name": "Drupal", "category": "CMS", "evidence": "meta generator \"Drupal 11 (https://www.drupal.org)\"" }, { "name": "Google Tag Manager", "category": "Tag manager", "evidence": "html GTM noscript iframe" }, { "name": "Fastly", "category": "CDN", "evidence": "header x-served-by" }, { "name": "Apache", "category": "Web server", "evidence": "header server" }, { "name": "jQuery", "category": "JS library", "evidence": "script src /jquery([.-]\\d[\\d.]*)?(\\.min)?\\.js/" } ], "capturedAt": "2026-10-16T05:53:25.120Z" } ]``` {% endraw %} Failed rows come back with an {% raw %}`error`{% endraw %} field instead of technologies, so you can retry or drop them. ## Be realistic about accuracy This is a coarse tool, and my test run shows why: - {% raw %}`https://www.shopify.com`{% endraw %} returned only **Cloudflare**. A single request saw nothing else. Absence of a detection is never proof a technology isn't used. - {% raw %}`github.com`{% endraw %} came back as GitHub hosting plus Contentful, not a full stack. - No JavaScript is executed, so tech that appears only after client-side rendering, or only on other pages, is missed. No version numbers are reported (except what a generator tag states). - Sites behind bot walls or logins may return a block page. No proxies or captcha solving are used. It's best for questions like "which of these 500 are on WordPress / Shopify / Cloudflare?", where the signal is in headers or the HTML, and weaker for building a complete technographic profile. I didn't run a 500-URL batch for this post, so I won't quote timing for one. Try 20 of your own sites first and compare with what you know. ## Call it from code Small lists, one synchronous request: {% raw %} ```bash curl -X POST \ "https://api.apify.com/v2/acts/pennydata~website-tech-stack-detector/run-sync-get-dataset-items?token=$APIFY_TOKEN" \ -H "Content-Type: application/json" \ -d '{"urls":[{"url":"https://wordpress.org"},{"url":"https://nextjs.org"}]}'

For 500 URLs use an async run with the Python client:

from apify_client import ApifyClient client = ApifyClient("YOUR_APIFY_TOKEN") urls = [{"url": u.strip()} for u in open("sites.txt") if u.strip()] run = client.actor("pennydata/website-tech-stack-detector").call( run_input={"urls": urls, "maxConcurrency": 10} ) rows = client.dataset(run["defaultDatasetId"]).list_items().items wordpress = [r["input"] for r in rows if "WordPress" in r.get("technologyNames", [])] print(len(wordpress), "WordPress sites out of", len(rows))

technologyNames is a flat list for easy filtering; technologies has name, category and evidence per detection.

Wrap-up

For a few dollars you can tag a whole prospect list by CMS, ecommerce platform, CDN and analytics, with the evidence attached. Treat it as a first-pass filter and verify anything important by hand.

Written with AI (Claude).