Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, to verify whether an interaction with a particular content displayed on a content platform is an interaction by an actual human user. A request to generate a click verification token can be received from a first application executing on a client device. The request can include data for a first set of parameters for a first interaction and a first message authentication code (MAC) set. If the first MAC set matches a second MAC set, which is generated using some of the data included in the request, the click verification token can be generated. The click verification token can be provided to the first application, which in turn can provide this token to a content verification system. The content verification can use this token to verify whether the first interaction is an actual human user interaction.