ipstack - ipstack is a free, real-time IP address to location JSON API and database service supporting IPv4 and IPv6 lookup.
DiscoverOrg - DiscoverOrg is an IT sales intelligence platform providing technology marketers access to data, IT org charts, and real time projects.
ipapi - Web analytics with IP address lookup and location API
Clearbit - Clearbit provides Business Intelligence APIs
ipinfo.io - Simple IP address information.
Datanyze - The sales prospecting tool powered by technology data