What are some alternatives?
When comparing ipstack and ipgeolocation.io, you can also consider the following products
ipapi - Web analytics with IP address lookup and location API
IP-API.com - Free IP Geolocation API - lookup any IP address
IP2Location - IP2Location is a leading provider of IP intelligence service.
ipdata.co - Get the Geolocation, Organisation, Currency, Timezone, Calling Code, Flag, Proxy, Tor and Threat intelligence data from any IPv4 or IPv6 address.
WIPmania - WIPmania provides a number of free products and services based on WorldIP geolocation database.
Geo IP Tool - Find a geolocation of an IP address including latitude, longitude, city, region and country.