Systems and methods are provided for synchronizing messages. The systems and methods include operations for: receiving, from a server by a client device, a set of synchronization data representing changes since a previous time the client device synchronized with the server; comparing, by the client device, the set of synchronization data to a local state of the synchronization data; identifying a difference between the set of synchronization data and the local state of the synchronization data; and transmitting, to the server by the client device, a request for content corresponding to the difference between the set of synchronization data and the local state of the synchronization data.