ipstack - ipstack is a free, real-time IP address to location JSON API and database service supporting IPv4 and IPv6 lookup.
WIPmania - WIPmania provides a number of free products and services based on WorldIP geolocation database.
ipapi - Web analytics with IP address lookup and location API
GeoNode.org - Open Source Geospatial Content Management System
ipgeolocation.io - Free IP Geolocation API and Accurate GeoIP Lookup Location Database
HERE - HERE provides APIs and solutions to build location-aware web and mobile apps.