It was developed for Stardock as part of their ThinkDesk subscription service, but is available separately.
It is closer in concept to a KVM switch, but while these have multiple cables to each computer, with Multiplicity the keyboard and mouse remain connected to the host computer and input is forwarded from the host to client machines via network connections — typically over TCP/IP port 30564.
[2] Switching is triggered by movement of the mouse to the appropriate side of the screen (or keyboard shortcuts, if desired), both from the desktop and in full-screen video modes.
Multiplicity can emulate the capability of the KVM switch and let one display serve all the connected computers.
Multiplicity does not permit combining computers with different operating systems, like macOS and Linux.