Pydio is the mature open source alternative to dropbox and box.com, for the enterprise.
Why building your own box?
You need to access your documents across multiple devices, and regularly share documents (weblinks) and folders with your contacts and teams. Still, using a consumer SaaS box or drive service is neither practical nor safe. And enterprise SaaS box or drive services are expensive and come with Disk Storage that you already have on your servers or private cloud.
How to build your own box with Pydio?
Easily install Pydio on your servers or cloud of choice, Simply share documents and folders with your teams, Administrate your box with an Entreprise grade console (rights, groups, plug ins), Access documents with a Web Gui, Smartphones and tablet apps (iOS, Android), Sync folders on your computer (public beta, PC, Mac, Linux,Web,Tablets).