This class can backup local files as a ZIP archive sent to Dropbox
It handles the OAuth authorization process to obtain a token to access an API on behalf of the current Web user.
The class create a ZIP archive with files from a directory to backup.
The ZIP archive is sent to the DropBox server using requests sent to is API.
http://www.phpclasses.org/package/8922-PHP-Backup-local-files-as-a-ZIP-archive-to-Dropbox.html
Does your team, company, family want your own dropbox, mega.co.uk, meocloud.pt or similar running on your own infrastructure? afraid of NSA, CIA or KGB spying your data?
ownCloud gives you universal access to your files through a web interface or WebDAV. It also provides a platform to easily view & sync your contacts, calendars and bookmarks across all your devices and enables basic editing right on the web. Installation has minimal server requirements, doesn’t need special permissions and is quick. ownCloud is extendable via a simple but powerful API for applications and plugins.
http://owncloud.org/
SparkleShare creates a special folder on your computer. You can add remotely hosted folders (or “projects”) to this folder. These projects will be automatically kept in sync with both the host and all of your peers when someone adds, removes or edits a file.
http://sparkleshare.org/