Crunchbase - Crunchbase is a platform for discovering industry trends, investments, and news about companies around the world.
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
CB Insights - CB Insights is a company database for the venture capital and corporate development community.
BuiltWith - Find out the technology behind websites
PitchBook - PitchBook is an award winning data & technology provider for the global private equity and...
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.