Every website is built from a stack of visible and hidden technology: a CMS, a JavaScript framework, analytics scripts, payment providers and more. A technology detector extension reads signals in a page's code, such as script sources and HTTP headers, and matches them against known signatures to tell you what a site is built with, without viewing source manually.
How a technology detector extension works
These extensions scan a page's HTML, JavaScript files, cookies and response headers for patterns that match known software, such as a specific script filename used by a CMS or a meta tag added by a page builder. When a match is found, it's grouped into categories like CMS, ecommerce platform, analytics or advertising and shown in the toolbar popup.
What you can and can't detect this way
Detection works well for client-visible technology: CMS platforms, JavaScript frameworks, analytics, tag managers and ecommerce platforms all leave signatures in the page. Server-side languages, databases and backend infrastructure usually aren't detectable this way, since they never appear in what the browser downloads.
Common uses for a tech stack finder
Developers use these extensions to see how a competitor built a feature, sales and marketing teams use them to qualify leads by the platform a prospect runs on, and researchers use them to survey which frameworks and tools are common across a set of sites without checking each one manually.