open source software (LGPL)
free backup client that securely stores encrypted, incremental, compressed backups on cloud storage services and remote file servers
Features:

   Duplicati uses AES-256 encryption (or GNU Privacy Guard) to secure all data before it is uploaded.
   Duplicati uploads a full backup initially and stores smaller, incremental updates afterwards to save bandwidth and storage space.
   A scheduler keeps backups up-to-date automatically.
   Encrypted backup files are transferred to targets like FTP, Cloudfiles, WebDAV, SSH (SFTP), Amazon S3 and others.
   Duplicati allows backups of folders, document types like e.g. documents or images, or custom filter rules.
   Duplicati is available as application with an easy-to-use user interface and as command line tool.
   Duplicati can make proper backups of opened or locked files.

Read Duplicati HowTos guide for complete instructions. http://www.duplicati.com/howtos