My need is to have a simple web form that also lets people upload some pdf's. What I was thinking I could do (because of the size and number of uploaded files) is to tie the backend of this app to either my dropbox account or my box.com account. Both services offer similar API's to build apps.
However they both assume I want to interact with people's dropbox/box account. I think I kinda want the reverse of that. People would upload files to a web server but I want to upload them programatically to either of these 2 services, but under MY account with access and permissions related only to MY account.
The users don't need to interact with dropbox at all, they don't need to approve anything. Why doesn't it seem possible to use the API in such a way that files can be added to the same, previously known, dropbox account which I own?
While this isn't the intended use, the basic idea would be to manually get an authorized access token for the account once, and save and reuse it for all future calls. (Just be sure not to revoke it.)
It is essentially the same way you would manage multiple users, except that each user just reuses the same access token, instead of their own.