Simple Analytics - The privacy-first Google Analytics alternative located in Europe.
BuiltWith - Find out the technology behind websites
Fathom Analytics - Simple, trustworthy website analytics (finally)
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
Plausible.io - Plausible Analytics is a simple, open-source, lightweight (< 1 KB) and privacy-friendly web analytics alternative to Google Analytics. Made and hosted in the EU, powered by European-owned cloud infrastructure 🇪🇺
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.