Systems and methods that synchronize indexes are described. In one embodiment, a first index on a first client can be provided, wherein the first index comprises a plurality of terms associated with a plurality of events, the events comprising client activity associated with an article, and the first index can be synchronized with a second index or a second client by sending events from the first client to the second client, wherein the first and second indexes index the same events. In another embodiment, an event is retrieved from a first client, wherein the event comprises event data, the event is sent to a second client, the event is received by the second client as a new event, the new event comprising event data, a new event ID is associated with the new event, the new event ID is indexed, and the new event is stored.