An application platform system and method. A data synchronization instance manages a reference state object for a data synchronization system (DSS) account. A first local state object is stored at a first application system. The first application system receives update notifications provided by the DSS. A second local state object is stored at a second application system. The second application system receives update notifications provided by the DSS. An application instruction of the first application system is transformed into a state update, and the first local state object is modified to include the state update. The state update is provided to the DSS via a local update notification. The reference state object is modified to include the state update. The state update is provided to the second application system via a reference update notification. The second local state object is modified to include the state update.