IP-API provides free usage of its Geo IP API through multiple response formats. It supports IPv4 and IPv6. IP-API's system will automatically ban any IP addresses doing over 150 requests per minute. You are free to use ip-api.com for non-commercial use. It does not allow commercial use without prior approval. For commercial, unlimited service, you have to subscribe to its Pro service.
IPV6 lookups are currently supported by Maxminds services like GeoIP2 Precision, Geo IP2 Legacy and minFraud services, GeoIP2 Country and City, GeoIP2 Domain Name and GeoLite2 databases. IPV6 support is also provided free ofGeo-Location API Services MaxMind