A peer-to-peer synchronization protocol for multi-premises hosting of digital content items. In one embodiment, for example, a method comprises the operations of: receiving, from a peer computing device, a peer download advertisement comprising an identifier of a content item namespace in association with a peer client journal cursor value; receiving, from a server, one or more server journal entries, each identifying one or more content item blocks of a content item represented by the server journal entry and each having a server journal cursor value; and for at least one server journal entry, downloading, from the peer computing device, at least one content item block of the content item represented by the server journal entry that is not already stored at the computing device.