DomainTools - Domain name research, including comprehensive Whois Lookup, Reverse Whois Lookup and Whois History.
WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.
JsonWhois.io - JsonWhois is the leading cloud hosted Whois API.
WebCargo - Optimize your workflow by offloading it to us. Useful API's with seamless integration that scale to your needs.
CubDomain - CubDomain.com is the site to check website's statistics, Information, Whois Record, Hosting...
Bulk Whois API - Bulk Whois API is a provider of parsed WHOIS data in JSON with simple API, competitive pricing, top notch support, and more.