Techniques for integrating two server systems are provided. A first server system receives, from a first computing device, provider data generated by a third-party tracking service. The first server system stores association data that associates the provider data with one or more content items. After storing the association data, the first server system receives, from a second computing device, a message that includes a first identifier and that indicates an event and a content item. In response to receiving the message, the first server system determines whether to report the event to the third-party tracking service. If so, the first server system determines a second identifier based on the first identifier, retrieves, based on the association data and the content item, the provider data that is associated with the content item, and transmits, over a network to the third-party tracking service, the second identifier and the provider data.