WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.
ipinfo.io - Simple IP address information.
WebCargo - Optimize your workflow by offloading it to us. Useful API's with seamless integration that scale to your needs.
IPTools - The "IP Tools" is powerful and handy application for network analyzing.
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.
ipdata.co - Get the Geolocation, Organisation, Currency, Timezone, Calling Code, Flag, Proxy, Tor and Threat intelligence data from any IPv4 or IPv6 address.