Systems and methods for controlling ad delivery to mobile clients while maintaining user privacy are herein provided. One exemplary method involves a location broker service. The method includes receiving, at an ad delivery service, a location use token from a mobile client, which may be a single use token. The method includes sending, from the ad delivery service, the location use token to the location broker service for verification at the location broker service. The method includes receiving, at the ad delivery service, the mobile client location from the location broker service based on the verification. The method includes delivering, from the ad delivery service, a location-targeted ad to the mobile client at the mobile client location, where the delivering is further based on a geographic density of a plurality of mobile clients. An advertiser using the ad delivery service may be billed based on location use token history.