I need to write a batch file to auto upload a backup every day. I'm restricted to Windows. Is there free software to do this?
SFTP and FTPS are both encrypted in similar fashion, BUT there is a BIG difference between their deployment and use.
However, from what I can gather, you need a FTP client for both. Filezilla is a good one that users I've dealt with never complained was too hard to figure out.
To use SFTP, you need a key exchange. To use FTPS, you issue self-signed or CA certificate AND don't need to issue private keys.
Overkill is to get to sftp, but Cygwin is a nice toolset. Depending on your needs, you could scale the install back to only the minimum you need or scale it up and use Bash, Python, etc. instead of a batch file.