Services/Sync/Server/API
From MozillaWiki
Firefox Sync APIs
The Sync APIs are divided up into a series of components to handle various tasks in the service chain. At this time, there are two APIs, one for setting up and managing an account (User) and one for synchronizing data with the server (Storage).
http://docs.services.mozilla.com/ documents the Sync API and response codes, and other Mozilla web services.