Need an SFTP server ? Want one for free?

In setting up a duplicate environment to host a backup copy of  a clients web site (for contingency purposes) a secure FTP server was requested by the web design company to allow transfers of the live site backups to be sent to this backup server. I had provided a costed SFTP solution for a client some time ago but wanted to see if a lower cost option was available. I had used a product from Core FTP for a client solution for SFTP transfers so it was logical to see if they had any options. When I found this free server I was very happy.
There is some documentation on getting set up here. I will be testing further for the client as part of this project but this certainly looks worth a check
PS From the documentation re secure access setup
There are three different secure security protocols available with Core FTP Server: SSL/TLS, SSH2/SFTP, and HTTPS.
The main reason for using secure FTP connections is to protect your account information (which is passed in clear text across networks with standard FTP) and data from being seen by ‘unwanted’ or ‘prying’ eyes on networks.
SSL and TLS are the more commonly used secure FTP options for transferring files.   This option will protect your login information from being displayed, as well as your files.   SSL and TLS connections are established after the request has been issued by an FTP client.   This option is enabled by default.
You can disable SSL or specify that only SSL connections be allowed, in the domain setup screen.The SSL direct option involves a direct SSL connection with all data being encrypted as soon as a connection is established..   To enable this option, select the ‘SSL direct’ option in the domain setup screen. SSH2/SFTP is a less common form of security used for secure FTP transfers, but offers the benefit of only one connection for transfers (whereas SSL/TLS involves two with the data channel often using a multitude of ports).   This can often be easier to implement when configuring firewalls or routers to allow secure FTP connections to pass through. It generally offers a wider span of encryption ciphers, as well as higher levels of encryption.
To enable SSH2/SFTP encryption, simply check the SSH/SFTP option in the domain setup screen. (If you are using private/public key pairs, Core FTP Server uses the OpenSSH format).HTTPS transfers are also supported (typically on port 443), check the HTTPS option in the domain setup screen.