I know I am late to the game. But just recently I discovered "OwnCloud". In my view OwnCloud is mainly a well designed server software which can be used and installed freely. The suite also includes some client-side Apps and some extensions - some of these additional tools require a purchase. When you install your own cloud server you essentially get a nifty cloud file storage solution with easy ways to upload through a browser, manage files and documents, share stuff and keep track of versions and basic collaboration features. You can check out all the details on their official site:https://owncloud.org/As I said I am fairly new to that game. And I just recently installed an OwnCloud server on a backup webspace that I maintain since Uni. It works really well and it is a good extension to my regular drobobox and onedrive accounts. Over the weeks I casually looked through the features and discovered nice ways to extend an OwnCloud installation. You can access it through many clients and out of the box it supports the WebDav protocol. Also I would like to mention: The mobile and desktop web client is also really really good.One nice way to expand is to add your external storage providers. I've done that with my Dropbox account and I was quite happy with having everything in a nice view through the lean web interface of OwnCloud.However since one or two days or so this solution stopped working. I.e. there were error messages in OwnCloud and I could not open my Dropbox folder via OwnCloud.It turns out that this OwnCloud external storage solution seems to use the OAuth 1.0 protocol as part of the Dropbox API v1. I feel that OwnCloud is already a fairly complex product and many enthusiasts work on the code and tirelessly want to improve the core and key features. The external Dropbox  solution seems to be a lower priority and it seems it was left untouched as Dropbox API v1 continued to work in parallel to the new Dropbox API v2. But just now on 28-September-2017 Dropbox really switched  off API v1.   :-(   for me this means - the just discovered option to use  Dropbox from within OwnCloud does no longer work.https://blogs.dropbox.com/developers/2017/09/api-v1-shutdown-details/I believe work will continue on that piece but I may need to stay patient. So OAuth 2.0 and consequently the new Dropbox API v2 needs to be incorporated in OwnCloud. People are already talking about this challenge and work has started:https://central.owncloud.org/t/gsoc17-dropbox-v2-integration/5901