IsHostedBy.com - IsHostedBy is a website where you can lookup where certain websites are hosted.

Whoisology - Connected database of whois records and whois history

Website Informer - Website.informer: complete data lookup & free aggregated report on any domain including whois, visitors, IP & DNS details, competitors, owners, etc

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.

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.

WhoisAPI - WhoisAPI is the premier provider of freshly parsed whois data for domain names and IP addresses...