When a client's offer hinges on a buyer's tech stack, BuiltWith is one of the technographic sources we lean on. It detects the technology behind any website, telling you which companies run a given CRM, ecommerce platform, ad pixel, analytics tool, or payment provider. The scale is what makes it useful. It scans more than 400 million domains and keeps over 18 years of usage history, so you can spot adoption trends and find every site that recently added or dropped a particular technology. A tech-stack match is a strong fit signal, especially when you sell something that integrates with or directly replaces a specific tool. You query by technology, keyword, or vertical, then export the matching domains with firmographics and contacts attached. We reach for BuiltWith on those accounts, not as a default source. When a client's pitch only makes sense to companies running a particular tool, we pull the matching domains, then enrich and verify them in Clay before any outreach starts. That ordering matters. The lists both seed brand-new campaigns and enrich existing accounts already in the CRM. The message angle ends up matched to what the company actually runs today, rather than a generic pitch that ignores their stack and gets ignored right back.