A synchronized media project, synchronization SDK, and synchronization service enable multiple users to produce a media composition collaboratively. A media project includes composition assets that reference media assets. A synchronization SDK enables multiple applications to edit the media project independent of an internal organization of the project. A project synchronization service synchronizes copies of media projects located on clients with a server-based versioned master project. User-selectable project synchronization modes determine whether media project assets are stored on clients, on the server, or on both, and when media assets are transferred. Synchronized media projects include composition assets in proprietary formats and in interoperable formats. Interoperable composition assets are rendered from proprietary composition assets on a track-by-track basis.