Startup Stash - A curated directory of 400 resources & tools for startups
BuiltWith - Find out the technology behind websites
Startup Buffer - Startup Buffer is a premium startup directory for emerging startups all around the world.
Wappalyzer - Wappalyzer is a technology profilers and leads data provider. Create lists of websites and contacts that use certain technologies.
Content Marketing Stack - A curated directory of content marketing resources
What CMS - WhatCMS.org looks at a variety of factors within a webpage to determine what CMS a website is using.