WinSCP - WinSCP is an open source free SFTP client and FTP client for Windows.
FileZilla Server - Download FileZilla Server 0.9.60.2 for Windows
Forklift - The most advanced dual pane file manager and file transfer client for macOS.
ProFTPD - The Official ProFTPD web site. ProFTPD is a high-performance, extremely configurable, and most of all a secure FTP server, featuring Apache-like configuration and blazing performance.
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.