This has been one of my favourite tools to use when I have had multiple computers with their own displays setup at my desk and faced the issue of cluttering my desk with numerous keyboards and mice.
For those who have never heard or come across a KVM before the acronym itself stands for “Keyboard, Video & Mouse” and is a device that interfaces a single keyboard, display and mouse with multiple computers. Modern KVMs can also include USB and audio output devices (like speakers or headphones). KVMs usually included hardware or software switches to swap between the various computers.
However, there are a few drawbacks to KVMs. Cable management can be an issue and the cables themselves can be an added cost that you would rather do without. Furthermore, traditional KVMs set a hard limit on the number of computers that can be connected by virtue of the number of ports available on the KVM.
Luckily, there is an alternative and it’s free!
Synergy is a FOSS (free and open source) project that aims to provide the use of a single keyboard and mouse across numerous platforms including Windows, Mac OS X and Linux all over a standard network connection (either Wi-Fi or wired). In a nutshell, one computer becomes a server to which other client computers connect. As part of the initial setup there is a configuration process that creates the awareness of where the screens connected to each computer are located with respect to one another (left, right, above or below). This essentially creates a large map of the screens with global coordinates with each computer owning a set of the coordinates which facilitates hand off of the cursor and keyboard input when the cursor goes off the edge of one screen to another connected to a different computer.
The only downside to using Synergy could be the fact that each computer needs its own display which could pose issues where there are not enough power points or power consumption is of concern. However, some people like to have visibility of all of their computers at the same time so it really comes down to personal preference.
Synergy is available here if you want to give it a crack!