Duplicati is a free backup client that securely 
stores encrypted, incremental, compressed backups on cloud storage 
services and remote file servers. It works with Amazon S3, Windows Live 
SkyDrive, Google Drive (Google Docs), Rackspace Cloud Files or WebDAV, 
SSH, FTP (and many more).  
Duplicati has 
built-in AES-256 encryption and backups can be signed using GNU Privacy 
Guard. A built-in scheduler makes sure that backups are always 
up-to-date. Last but not least, Duplicati provides various options and 
tweaks like filters, deletion rules, transfer and bandwidth options to 
run backups for specific purposes.
Duplicati is
 licensed under LGPL and available for Windows and Linux (.NET 2.0+ or 
Mono required). The Duplicati project was inspired by duplicity.
 Duplicati and duplicity are similar but not compatible. Duplicati is 
available in English, Spanish, French, German, Danish, Portugese, 
Italian, and Chinese.
Duplicati 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 using the Volume Snapshot Service (VSS) under Windows or the Logical Volume Manager (LVM) under Linux. This allows Duplicati to back up the Microsoft Outlook PST file while Outlook is running.
Why use Duplicati?
Keep
 your data safe, store it far away, update your backup regularly! This 
is a simple rule but many backup solutions do not achieve that today. 
But Duplicati does!
Keep your data safe! Bad
 guys on the Internet seem to look for interesting data everywhere. But 
people do not want to see any of their private data revealed anywhere. 
Duplicati provides strong encryption to make sure that your data 
looks like garbage to others. With a well chosen password your backup 
files will be more safe on a public webserver than your unencrypted 
files at home.
Store your backup far away! The
 best backup is useless when it is destroyed together with it's original
 data. Just assume that a fire destroys your office - would your backup 
survive? Duplicati stores backups on various remote file servers and
 it supports incremental backups so that only changed parts need to be 
transfered. This makes it easy to use a destination far away from the 
original data.
Backup regularly! The 
worst case is that your backup is outdated simply because someone forgot
 to make a backup at the right time. Duplicati has a built-in scheduler,
 so that it's easy to have a regular, up-to-date backup. Furthermore, 
Duplicati uses file compression and is able to store incremental backups
 to save storage space and bandwidth.