PLATFORM FOR THIRD-PARTY SUPPLIED CALLS-TO-ACTION

A first computing system provides an API to a third-party computing system. The first computing system receives via the API, from the third-party computing system, a registration API call including a registration request to associate an information item with a call-to-action defined by the third-party computing system. The registration request specifies the information item, the call-to-action, an underlying action, and a URL associated with the call-to-action. In response, the first computing system registers the call-to-action. After registering the call-to-action, the first computing system receives a request from a client device associated with a user of the social network. The request indicates that the user interacted with the information item at the client device. In response, the first computing system determines whether the information item is associated with the call-to-action. When it is associated, the first computing system sends the call-to-action to the client device for display.