Polo File Manager - Software for Linux
FTP Synchronizer - Secure and high performance FTP File Sync product
FreeFileSync - FreeFileSync is a free open source data backup software that helps you synchronize files and folders on Windows, Linux and macOS.
GNOME Commander - GNOME Commander is a "two-pane" graphical file manager for the GNOME desktop environment.
rsync - rsync is a file transfer program for Unix systems. rsync uses the "rsync algorithm" which provides a very fast method for bringing remote files into sync.
CLEX - CLEX is a command-line interface-based file manager for managing and editing project files, no matter where they are stored.