In my younger years, I was a heavy user of the Synergy tool ( in 2006), which allowed you to control multiple PCs (Linux, Windows) with a single keyboard and a single mouse.
But today, Synergy has evolved significantly and is no longer free. Fortunately, the next generation is here, and they go by the name Barrier.
Barrier operates its magic mainly through the local network, simplifying your setup and saving desk space if you have multiple computers but want to keep only one keyboard and one mouse.

Originally, Barrier is a fork (or clone, if you prefer) of Synergy, with its code available on GitHub. Like its parent, Barrier enables you to use a single keyboard and mouse across multiple machines. Barrier essentially emulates the function of a KVM switch, but in a software-based manner. So, when you move your mouse off your computer screen, it seamlessly lands on the screen of your second computer.

Barrier is available for Linux, including Linux ARM (making it suitable for Raspberry Pi), macOS, and Windows. As it closely resembles Synergy (with fewer bugs), all the tutorials and knowledge from the Synergy era can be applied to Barrier as well.
This is undoubtedly good news for users looking to simplify their multi-computer setups. You can download Barrier here