List of free profiling stuff for developerππ½
If you're looking for all programming tools around profiling (not just free). Check this page List of profiling Programming Tools

Wappalyzer
Find out the technology stack of any website. Create lists of websites and contacts by the technologies they use.
Tag: profiling, information, research
1 User 50 credits/mo

Similarweb
Similarweb is the ultimate competitive digital intelligence tool for a complete 360-degree view of your industry, competitors, and customers.
Tag: profiling, information, research
1 user Limited access to historical data

BuiltWith
Web technology information profiler tool. Find out what a website is built with.
Tag: profiling, information, research

whatruns
Discover what runs a website, a free browser extension that helps you identify technologies used on any website at the click of a button.
Tag: profiling, information, research