DomainTools - Domain name research, including comprehensive Whois Lookup, Reverse Whois Lookup and Whois History.
WebCargo - Optimize your workflow by offloading it to us. Useful API's with seamless integration that scale to your needs.
BuiltWith - Find out the technology behind websites
WhoisAPI - WhoisAPI is the premier provider of freshly parsed whois data for domain names and IP addresses...
WhatRuns - Extension that helps you identify technologies used on any website at the click of a button.
WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.