From EZC Group:
The YobiDrive Community Edition sharing platform comes bundled with YobiDrive FX for Enterprise, a professional file sharing allowing you to seamlessly share files with customers and partners. Share without limits, keep total control and access anywhere from a desktop, laptop, tablet or smartphone.
You can now install on premise or in the cloud of your choice a world class file sharing, in fact it is almost the same software as operated by the YobiDrive FX SaaS service and available on Google Apps.
This Community Edition is free for 10 users (managers and writers: readers are always unlimited so that you can send large files to unlimited users), and can be unlocked for more users depending on your kind of usage (unlimited for Non Profit Organisations).
A debian server or virtual machine with internet access is recommended, but the system can run on any computer running Apache 2, Tomcat 6 and Java 1.7 such as Windows or MAC OSX. We recommend to visit our Web Site for updated information. We also recommend you to contract some help from us or local specialists to refine the security setup (you should install a firewall and a server sll certificate if you don't restrict the usage to an intranet, and have your server configuration validated).
For developers, YobiDrive Community Edition exposes the Y3 API, allowing you to build your own file sharing applications that rock: to help you the full source code of the YobiDrive FX front end is open sourced under Apache 2 license.