The present invention provides a system and method for multi-tiered data synchronization. Data is synchronized between a master synchronization server, one or more proxy synchronization servers, and client devices. Client devices establish synchronization sessions with either a proxy synchronization server or a master synchronization server, depending on which server provides the “best” available connection to that client device. Each proxy synchronization server synchronizes data with client devices that have established a synchronization session with such proxy synchronization server. The master synchronization server synchronizes data with client devices that have established a synchronization session with the master synchronization server. Each proxy synchronization server synchronizes data with the master synchronization server. Metadata associated with synchronized files is synchronized throughout the system in real-time. Files may be synchronized in real-time or at a delayed time.