QuickSynergy is a graphical interface (GUI) for easily configuring Synergy2, an application that allows the user to share his mouse and keyboard between two or more computers.
Without the need for any external hardware, Synergy2 uses the TCP-IP protocol to share the resources, even between machines with diferent operating systems, such as Mac OS, Linux and Windows.
So QuickSynergy is a graphical user interface for Linux and Mac OS systems, since the official website presents only a Windows version.