BuiltWith offers website technology usage lookup for teams researching the technology mix of a public site.
It catalogs technologies seen on public sites.
When researching the technology mix of a public site, treat detection output as a lead for investigation.
Wappalyzer offers website technology stack identification for teams understanding frameworks used by a public site.
Censys offers internet asset and certificate lookup for teams checking public assets under an organization's domain.
Shodan offers internet device and service search for teams inventorying the exposure of one's public services.