Antida is data synchronization and backup software that works on any network that has Internet access. It allows automated backup to USB or any storage device. It can send files to any Web-enabled phone. Only a browser and Internet connection are required, with Antida on the other side of the data transfer. It can communicate with devices behind routers and firewalls on WANs.
csync is a bidirectional file synchronizer for Linux. It allows the user to keep two copies of files and directories in sync. It uses uses widely adopted protocols like SMB or SFTP so that there is no need for a server component of csync. It is a user-level program which means there is no need to be a superuser. With pam_csync, it is possible to create roaming home directories.