Usage of one Dropbox Account and connect to the same account from multiple sessions in an app

The API was designed with the intention that each user would link their own Dropbox account, in order to interact with their own files. It is technically possible to connect to just one account like you describe, but we don't recommend doing so, for various technical and security reasons, especially in client-side apps like on iOS or Android.

Doing so would involve embedding an access token for the desired account in the app itself. A malicious user could then extract that access token from the app though.

Also, the Dropbox API does have a rate limiting system, but we don't have any specific numbers documented. The limits operate on a per-Dropbox user basis, so if you have all of your end-users connect to the same account, you're more likely to hit rate limits. There isn't a way to disable the rate limiting.