Additional features
They all cover the basics, but what else can they do?
All of these programs permit synchronising one device with another, and that’s what we are looking at here, but some provide additional features that may make them more suitable for you. BitTorrent Sync ( btsync) makes sharing individual directories with other users easy, and read only if you prefer, by providing a link that can be emailed to the other user or you can display it as a QR code to make sharing with a phone easier. Sending links by email isn’t particularly secure, so you also have to approve the connection when they use the link. The free version of btsync only allows 10 directories to be synchronised, and some features are missing that are in the Pro version, costing from $40 a year.
Syncthing also has the option to send connection information via QR code and folders are labelled, so there’s no need for URLs to set up a share, just give the label once the connection has been established, but you have to connect the two devices first.
OwnCloud is in a league of its own when it comes to extra features. This is a full cloud file server that you run yourself, so you can share files and directories with anyone, allow others to upload and run other applications in the server, such as a calendar. If you only need to keep a few directories in sync it’s way over the top, but if you need the extra facilities yet want to control everything yourself, this is the one to look at first. Unison and Rsync are file synchronisers pure and simple.