ProxyCheck.io - proxycheck.io is a premium Proxy detection API with a full featured free plan. Try us today!
ipinfo.io - Simple IP address information.
IPlist.cc - Get IP details for free through the web or via API.
BigDataCloud IP Geolocation API - Next Generation IP Geolocation Technology and API. Provides confidence area in addition to conventional location estimation. Lightning fast API (sub-millisecond typical response time)
IP Sidekick - IP Sidekick is a geolocation API that returns information about an IP address.
ipapi - Web analytics with IP address lookup and location API