JsonWhois.io - JsonWhois is the leading cloud hosted Whois API.
WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.
ICANN WHOIS - The official ICANN WHOIS search for domain lookups.
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.
Domain Checker - Obtain domain name status information with this effective and intuitive application that allows you to batch process multiple entries. Domain Checker is a simple, but powerful whois lookup tool for users that require a domain availability analyzer.
Whoisology - Connected database of whois records and whois history