What are some alternatives?
When comparing WinSCP and ProFTPD, you can also consider the following products
FileZilla - FileZilla is an FTP, or file transfer protocol, client. It lets individuals transfer single files or batches to a web server. For many years, FTP was the standard for website design. Read more about FileZilla.
FileZilla Server - Download FileZilla Server 0.9.60.2 for Windows
Cyberduck - A libre FTP, SFTP, WebDAV, S3, Backblaze B2, Azure & OpenStack Swift browser.
vsftpd - Very secure FTP Daemon, a secure, fast FTP server for UNIX systems, including Linux.
Forklift - The most advanced dual pane file manager and file transfer client for macOS.
Titan FTP Server - Windows FTP Server with SFTP and SSL. Includes events automation.