To summarize what follows: The Datastore API may be a good idea if your data model is not highly structured and if your users mostly already have Dropbox accounts. As the docs note, each record has a unique ID, and the ID is a string, so you could store one record’s ID as a property on another record and treat it like a SQL foreign key. The binary value type is limited to 100kB, and above that you need to use Dropbox’s file API for the data and store the filename in the record instead.