With ownCloud you can sync & share your files, calendar, contacts and more. Access your data from all your devices, on an open platform you can extend and modify.  
  • Integration - ownCloud uses open standards to allow easy integration with your existing services. Use CalDAV, CardDAV, and WebDAV to sync your data along with many more.
  •   Privacy - ownCloud protects your privacy by allowing you to maintain control over your data. Server-side encryption can secure data hosted in external sources.
  • Open Source - All of the code running ownCloud is open source, allowing the public to openly review its security and anyone can contribute towards the development of ownCloud.

NOTE: There is a companion site (www.owncloud.com) which offers a commercial version for business. Unless you are interested in purchasing a large scale storage solution, be sure you are at the correct website.

https://owncloud.org/