Whoisology - Connected database of whois records and whois history
CubDomain - CubDomain.com is the site to check website's statistics, Information, Whois Record, Hosting...
WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.
JSON WHOIS API - Parsed domain WHOIS data from any WHOIS server via RESTful API with metered pay as you pricing.
WebCargo - Optimize your workflow by offloading it to us. Useful API's with seamless integration that scale to your needs.
Who Hosts This - Who-Hosts-This.com detects which hosting provider a website is using.