If I wanted to know what tech stack a site is using I would just pop open Maltego and find out. Which it seems like you are doing but just automating over a large list of companies and storing results in a db.
How do you use this to find a company's tech stack?
>Hacker News (sometimes abbreviated as HN) is a social news website focusing on computer science and entrepreneurship. It developed as a project of Graham's company Y Combinator, functioning as a real-world application of the Arc . programming language which Graham co-developed.
Maltego is pretty fun program, you can learn a lot with it. Viewing the tracking codes for a site can often reveal other sites a company owns, as a lot of companies are lazy and end up using the same tracking code on all the sites they own.