ipinfo.io - Simple IP address information.
FindHostName - Host Name and IP Address Checker
IPlist.cc - Get IP details for free through the web or via API.
FindSiteIP.com - Website IP Address & Host Name Locator
IP Sidekick - IP Sidekick is a geolocation API that returns information about an IP address.
Ipregistry - Ipregistry is a fast, reliable IP geolocation and threat data API. People use Ipregistry to personalize content, analyze traffic, target ads, block countries but also to prevent abuse by detecting Proxy and Tor users, known spammers and bad bots.