WhoisAPI - WhoisAPI is the premier provider of freshly parsed whois data for domain names and IP addresses...
ViewDNS.info - Free DNS related tools including Reverse IP Lookup, DNS Propagation Checker, Chinese Firewall Test...
DomainTools - Domain name research, including comprehensive Whois Lookup, Reverse Whois Lookup and Whois History.
Whats My DNS - Instantly check your domain names current IP address and DNS record information against multiple name servers located in different parts of the world.
JsonWhois.io - JsonWhois is the leading cloud hosted Whois API.
NsLookup.io - A simple and powerful tool for querying DNS records