How Does Wappalyzer Work?

How does Wappalyzer work? It is a browser extension and an API that read a web page the way a visitor’s browser does, then match the scripts, cookies, headers, HTML patterns and JavaScript globals they find against a rule set of technology fingerprints. Every rule that matches becomes a detected technology, grouped by category such as CMS, analytics or CDN.

How does Wappalyzer work, from page to report?

1. Load the page. The extension runs inside your browser and inspects each page you open. The website lookup and the API fetch the page from Wappalyzer’s own servers instead, so they see what an anonymous visitor sees and nothing behind a login.
2. Collect the evidence. It gathers script URLs, cookie names, response headers, meta tags, DOM patterns, CSS class names and the JavaScript variables a library leaves on the window object. That is a wider net than DNS-only tools, which is why it is good at spotting front-end frameworks.
3. Match the rules. Each technology has a rule: a regular expression on a script path, a header value, a cookie name. Rules can imply other technologies, so a WordPress plugin implies WordPress and PHP. Version numbers come from the same matches when the pattern exposes one.
4. Group and score. Matches are grouped into categories, and some detections carry a confidence value when the evidence is indirect. A page can trigger dozens of rules; the report is the deduplicated set.
5. Use it. Click the extension icon on any page for the live report, look up a domain on the website, export a list of domains by technology, or call the API to enrich a spreadsheet or a CRM. Paid plans gate the lists and the API; check the current pricing on Wappalyzer’s site.

Two things are worth knowing before you install it. First, the extension needs permission to read the pages you visit, since that is how it works; what it sends back and how long it is kept is governed by Wappalyzer’s privacy policy, which you should read rather than take our word for. Second, its rule set was open source for years and the company took the repository private in 2023, as far as we can tell, so the current rules are not something you can audit yourself. The limits are the same as any page fingerprint tool: it cannot see backend languages, the data stack, internal tools or the applicant tracking system unless the careers page loads it, and it reports on the page you open, not on the company. The short answer on what Wappalyzer is covers the product, Wappalyzer alternatives compares the options, and the technographics page explains which layers each method reaches.

Where JobsPipe fits

JobsPipe is a jobs data API. It collects live postings from LinkedIn, Indeed, Y Combinator, Naukri, Workday, Greenhouse, Workable, SmartRecruiters, Ashby, Lever and Paylocity, returns them as one schema with closure tracking and a ghost score, and includes a free tier of 1,000 jobs a month at jobspipe.dev. Posting-based detection is the complement to page fingerprinting: the technologies a company names in its job ads are the ones it runs behind the site. One scan combines both:

curl -X POST https://api.jobspipe.dev/v1/stack/scan \
  -H "Authorization: Bearer $JOBSPIPE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "domain": "stripe.com", "mode": "auto" }'

The same lookup is available to agents through the detect_company_tech_stack tool on the MCP server.