credit: https://owncloud.org/features/

Access, Sync and Share Your Data, Under Your Control!

ownCloud is a self-hosted file sync and share server. It provides access to your data through a web interface, sync clients or WebDAV while providing a platform to view, sync and share across devices easily — all under your control. ownCloud’s open architecture is extensible via a simple but powerful API for applications and plugins and it works with any storage.

Access everything you care about

Store your private pictures, documents, calendar and contacts on your ownCloud server at home, a rented VPS or use one of the public ownCloud providers. Access your existing data on an FTP drive at work, images shared with you on Dropbox, or your NAS at home--all through your ownCloud server.Run your ownCloud server in a place you trust and access all the data you care about in one place!

Your data is where you are

When traveling, access ownCloud through your Android or iOS devices. Automatically upload pictures after taking them. Sync files at home or work with the desktop client keeping one or more local folders synchronized between devices. And wherever you are, the web interface lets you view, share and edit your files alone or with others.
Wherever you are, your data is with you thanks to ownCloud!

Share with anybody on your terms

Send password protected public links so others can upload files to you; get notified on your phone when you get a share from your own or another ownCloud server. Edit documents together, have video calls over your own server, comment on pictures shared with or by you. Don't be alone!
With ownCloud, you easily share and collaborate with whomever you want.