FTP Synchronizer - Secure and high performance FTP File Sync product
GNOME Commander - GNOME Commander is a "two-pane" graphical file manager for the GNOME desktop environment.
FTPSync.pl - FTPSync.pl is a PERL skript to synchronize a local directory tree and a remote FTP directory tree.
FreeFileSync - FreeFileSync is a free open source data backup software that helps you synchronize files and folders on Windows, Linux and macOS.
Polo File Manager - Software for Linux
Syncany - Syncany is an open-source cloud storage and filesharing application.