InterestExplorer - Discover 1000's of hidden Facebook interests to target.
BuiltWith - Find out the technology behind websites
upRive - Create and scale Facebook ads quickly and efficiently
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
AdEspresso - Optimize your Facebook Ads Easily, Like Morning Coffee
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.