What are some alternatives?
When comparing IP-API.com and Ipregistry, you can also consider the following products
ipgeolocation.io - Free IP Geolocation API and Accurate GeoIP Lookup Location Database
ipinfo.io - Simple IP address information.
ipdata.co - Get the Geolocation, Organisation, Currency, Timezone, Calling Code, Flag, Proxy, Tor and Threat intelligence data from any IPv4 or IPv6 address.
IP2Location - IP2Location is a leading provider of IP intelligence service.
ipstack - ipstack is a free, real-time IP address to location JSON API and database service supporting IPv4 and IPv6 lookup.
IPTools - The "IP Tools" is powerful and handy application for network analyzing.