Bittorrent Sync

Always the latest version? Try Bittorrent Sync:

BitTorrent Sync by BitTorrent, Inc is a proprietary peer-to-peer file synchronization tool available for Windows, Mac, Linux, Android, iOS and BSD. It can sync files between devices on a local network, or between remote devices over the Internet via secure, distributed P2P technology. All transfers are encrypted.

Multipar Bittorrent Sync keys:

Multipar - Releases
Multipar - Sources