Grsync is a rsync gui, a graphical user interface for the rsync file synchronization and backup tool. It works on linux, solaris, windows, mac os x and maemo. It uses the gtk libraries and can work under the gnome desktop.
It doesn't need the gnome libraries to run, but can of course run under gnome pretty fine. It can be effectively used to synchronize local directories and it supports remote targets as well (even though it doesn't support browsing the remote folder). Sample uses of grsync include: synchronize a music collection with removable devices, backup personal files to a networked drive, replication of a partition to another one, mirroring of files, etc.
Features
* Most commonly used rsync options available, additional options may be specified by command line switches * Saves multiple settings with customized names (no limit on number of "sessions") * Can do simulation or normal execution * Captures and prints rsync output nicely on a own window and log to a file * Parses rsync output to display progress bars and other information * Highlights errors and show them on a separate window, for better and faster control over rsync runs * Can pause rsync execution * A good number of translations available * Can run custom commands before (and stop in case of failure) and after rsync * Shell script for batch, crontab use etc. provided (grsync-batch) * Can import and export sessions on file; i.e. share your settings with people! * Can minimize to system tray (status icon) * Can run specific sessions with superuser privileges * Rsync backup made easy! * Needs rsync installed on the system (command line tool only, no need for server-side daemon) and GTK * Available for free and with sources! * Works on many linux distributions (including Nokia Maemo), Mac OS X and windows!
SyncToy 
grsync is not discontinued as the site states and works fine even in 2020.