Duplicati 2.0 is free backup software and open source. It is quite unique among many such free backup programs. The web-based user interface is clean and logical, although some of the more advanced features are hidden by default and you may want to pay notice to this. It runs extremely efficient and fast compared to many commercial counterparts. The storage requirements for backup are also amazingly slim. You can store many versions of the backup in the same location without worrying about overflowing the disk. File restoration also works perfectly. Duplicati 2.0 offers a serious alternative to File History that came with Windows in terms of the overall backup strategy.