
FreeFileSync
FreeFileSync is a free Open Source software to synchronize files and synchronize folders available for Windows, Linux and Mac OS X.
DirSync is a directory synchronisation tool, which can also be used for backupping data.
DirSync is an intuitive backup tool that can be run without installation. By comparing source and target files, only required files are copied, which greatly increases the working speed. By using multiple jobs, it is possible to perform complex data backups.
DirSync can work with drive serial number instead of drive letters.
portable file-synchronization folder-sync
FreeFileSync is a free Open Source software to synchronize files and synchronize folders available for Windows, Linux and Mac OS X.
Free Open Source Mac OS X Windows Linux Debian CentOS Ubuntu openSUSE
The only automated sync, back-up, collaboration and file management service powerful enough for a business user and easy enough for a novice. Secure, anywhere access to your files.
Freemium Mac OS X Windows Android iPhone iPad Web
ChronoSync can synchronize, backup, and create bootable backups to almost anything you can connect to your Mac: select cloud services, other Macs, NAS drives, external drives, PC's or anything you can mount as a volume.
Commercial Mac OS X
FolderSync enables simple and automatic sync to cloud based storage to and from local folders on the device memory card. It currently support multiple SkyDrive, Dropbox, SugarSync, Ubuntu One, Box.
Freemium Android Android Tablet Kindle Fire