What is the way to synchronize a 50-100GB file on ftp?

Question

Backup

you need to send backups to the ftp / sftp server, the backups themselves have already been made, in fact, you need to synchronize the user's folder with the folder on the server.
But the question arose of the slow Internet, if all this does not go in 1 working session, you need some kind of "resume" mechanism,
who can advise what? It is a pity that the user would be less tempted to turn it all off and complicate the work of sys.amides
For small files, I use the WinSCP console version and the script in the scheduler everything is clearly synchronized, I don’t know how it will work with large files, and maybe someone has a better way

Answer 1

rsync can only sync the changed chunks in a large file.
I answer in advance to "oh, I have Windows": cygwin allows you to use most of the nix utilities on Windows.

Answer 2

syncthing\ synctrayzor