FreeFileSync is a free Open Source software that helps you synchronize files and synchronize folders for Windows, Linux, and Mac OS X. It is designed to save your time setting up and running backup jobs while having nice visual feedback along the way.
FreeFileSync imposes no artificial limitations on how many files you can sync. Practically speaking, the only limiting factor for extremely large sync jobs is the amount of free memory available: For each 1 GB of RAM, FreeFileSync can synchronize roughly 1.7 million file pairs at a time.
Features of FreeFileSync:
Synchronize network shares and local disks.
Synchronize MTP devices (Android, iPhone, tablet, digital camera).
Synchronize via SFTP (SSH File Transfer Protocol).