Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
Clearbit - Clearbit provides Business Intelligence APIs
BuiltWith - Find out the technology behind websites
LinkedIn Sales Navigator - Sales tool for LinkedIn users.
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.
Clearbit Connect - Clearbit Connect is a free extension that surfaces actionable information on the people who email you.