Mobile Application(IOS and Android)

The issue is that client-side applications can't keep secrets, meaning that any access token stored in a distributed app, or even just sent to the app at any time, could be extracted. That means that a malicious user could get the access token, and use it to access the Dropbox API directly, bypassing any access controls your app attempted to enforce. (E.g., they could download files.)

However, if you have your own server and are willing to use that as an intermediary, you do have more options. You could have the app call to your server, and have your server call the Dropbox API. That way, you can protect your access token on the server.

In that case, you can either:

a) have the mobile apps upload to your server, and then have the server upload to Dropbox (e.g., to /2/files/upload).

b) have the mobile apps call your server, have the server call /2/files/get_temporary_upload_link, and return the resulting upload link to the app. The app could then upload directly to Dropbox using the link. (Note that /2/files/get_temporary_upload_link is still in preview though.)

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