Duplicati

This review is based on the "experimental" version 2.0.

Duplicati is fantastic software for backing up your files. It works on Mac, Windows and Linux. You select a folder or folders for it to keep and eye on, and corresponding folders where your backed up files should end up. It then asks for a schedule - how often it should look for changes and make a backup. It can listen every six minutes or more. The interface is based in your internet browser, a little bit like SyncThing, but even smoother in the way it works.

Although Duplicati has built in support to talk directly to online Sync/backup services, such as Dropbox, this is a little unnecessary, since you can tell the clients of such services simply to watch out for a particular folder, and you can choose the destination folder discussed above.

More impressive is that Duplicati comes with optional encryption for your files. When choosing the folder the app is watching, you choose also the encryption option and a (hopefully strong) password. With that setup, Duplicati will not only produce a backed up verion of your files, but encrypt them along the way using the very strong AES-256 standard. This way, if the destination folder is being monitored by a backup or sync client (e.g. of Dropbox), only encrypted versions of your files will be put into the cloud. That is very important for maintaining your online privacy, because Dropbox and related services have access to all your files, and have been known to a) get hacked, b) pass on people's info (files included) to law enforcement. Duplicati even hides the size and structure of your files. If you use encryption to backup, say, a 700 Mb file (ahem), the encrypted output from Duplicati will be 14 x 50MB files, which are unreadable to anyone who doesn't have the password. Moreover, to restore a file from backup, you enter the password and it restores the file structure in a menu, so you can pick what you want from all the files you backed up without having to decrypt/restore everything (unless you want to).

The only comparable app to this is Cryptomator, which also encrypts on a file-by-file basis, but is more tuned to syncing than to backups. (Check that out also: it's excellent for protecting your privacy if you're using the Cloud.)

Duplicati is brilliant, and the developer deserves a medal. Or, if you prefer, a donation. It's really a great thing that software this useful is freely available and open source. Highly recommended.

This seems very poorly designed.

You can try to backup ~2 TB of data and it says that it needs to backup 600 TB(!), probably from following recursive symlinks or something? There's no obvious way to find out where the links are or how to exclude them.

Or it tells you there's been an error, and when you click "Show" it shows a list of plain text dates that aren't obviously clickable. If you click one, it shows you a dump of json(?) code that means very little. You can search for "error" and try to find the errors that way.

If you've requested a folder to be backed up and the folder is then deleted, Duplicati just stops backing up anything! Your data could very easily be lost.

[Edited by endolith, July 16]

After months of using this, I've lowered my rating to the worst score. It's highly buggy and poorly-written, and there's little helpful support on their forum.