Bloomberry is a tool that tells you what SaaS products a company uses (in addition to what companies uses a specific product).
Unlike Builtwith, which focuses mostly on frontend technologies, Bloomberry also tells you what enterprise tech products a company uses (not just frontend). So stuff like devops tools, status page tools. CRMs, AI products, project management tools, etc. While its definitely not 100% coverage of everything, it covers a lot more than Builtwith.
The tools looks at the javascript files embedded on a company website, but it goes further than that. It looks at a company’s dns records (often used to validate their domain for sso), internal subdomains created (ie git.domain.com), certificate transparency logs, changes to subprocessor lists and more.
Right now the tool covers 5 million companies so if you search for small 1-man bootstrapped startup you probably wont get any results. I recommend trying it for any medium or large sized company instead :)