Product Recommendations AI - Personalized software recommendations based on your stack
BuiltWith - Find out the technology behind websites
FoundersList - Everything you need for your startup or new business
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
Stackshare - StackShare is a comprehensive website that gives its users the chance to organize and share their technology stack with the rest of the community.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.