NOTE: "Beta" means that BitTorrent Inc. has fixed all the significant bugs that have been identified and is now releasing a version that is probably close to the final version.BitTorrent Sync is useful for syncing files between devices. The new service is very much like Dropbox but with one major difference: it doesn't store any files on anyone else's servers. In fact, it doesn't store any files anywhere in the cloud. It only copies files directly from one computer you own to another computer you own (or to a friend's computer that you explicitly allow into your personal "network") without intermediate storage anywhere else. This is accomplished by using peer-to-peer technology: all files are copied directly from one of your computers to another of your computers with no intermediate servers involved.
BitTorrent Sync was designed with privacy and security in mind. All the traffic between devices is encrypted with AES cypher and a 256-bit key created on the base of the secret—a random string (20 bytes or more) that is unique for every folder. As a result, your data remains secure and hidden from anyone else.
BitTorrent Sync is still free, simple to use, and secure. BitTorrent Sync has always been available for Windows, Macintosh, and Linux. BitTorrent has now added an Android application and an Apple iOS app is promised to be available soon.
If you want to share files with a friend or relative, or if you want to copy files from the office computer to a home computer (or vice versa), or want to keep backup copies of your important files "off site" at another location, BitTorrent Sync may be the perfect program for you. It is also good for sending very large video files to friends and family when those files are too big to easily send by email or other methods.
The free BitTorrent Sync file copying program may be found at http://labs.bittorrent.com/experiments/sync.html.