HubSpot - Grow Better With HubSpot: Software that's powerful, not overpowering. Seamlessly connect your data, teams, and customers on one CRM platform that grows with your business.

BuiltWith - Find out the technology behind websites

EngageBay - EngageBay is an affordable all-in-one marketing, sales CRM and service helpdesk software for growing companies to acquire, engage and nurture web visitors to happy customers.

Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.

Marketo - Marketo's powerful marketing automation software helps marketers master the art & science of digital marketing to engage customers and prospects.

What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.