Question: I'm looking for a service that can help me determine a user's location based on their IP address for targeted advertising.

If you need a service to figure out a user's location by their IP address for targeted advertising, ipdata is a good option. It offers a detailed IP Geolocation API that includes geolocation data, threat intelligence feeds, proxy and VPN detection, company information and IP reputation scores. That information can be used for targeted ads, geographic restrictions and blocking spam and abuse. The API is available in several pricing levels, including a free tier for non-commercial use, and has high availability and uptime.

Another good option is MaxMind, which offers real-time risk scoring and insights for fraud prevention along with detailed IP geolocation data. MaxMind uses machine learning to help businesses create safer and more personalized digital experiences. Its proxy detection means you can block unauthorized access from VPNs, proxy users and anonymizers, and it's good for companies of all sizes.

Ipregistry offers a more powerful system for identifying and profiling users, blocking fraud and analyzing logs. It offers detailed IP Geolocation and Threat Intelligence data, with more than 3 million unique locations. Threat intelligence from more than 220 OSINT feeds and JSON and XML APIs make Ipregistry a good choice for publishers, ad networks, e-tailers and financial services trying to personalize content and block online fraud.

Last, IP-API offers a full geolocation service that includes country, region, city, latitude, longitude and ISP information. It offers detailed network information and is designed to help businesses reach a global audience, increase conversions and automate user experiences. The API is secure and easy to use with HTTPS/SSL encryption and supports several programming languages, so it's a good tool for improving security and personalizing user experiences.