Software tools let one keyboard and mouse control two PCs without a KVM switch

KVM switches, named for keyboard-video-mouse, predate USB and even the mouse, TechRadar reported. PCs have supported multiple monitors since the 1980s, with Mac leading and Windows adding integrated support in Windows 98. Studies cited by the publication have shown people are generally more productive on two monitors than one, which has driven interest in KVM deals. A third scenario goes further: two PCs, each with its own display, controlled by one keyboard and mouse.

Reasons include rapid switching between a coding PC and a development target, keeping multiple platforms visible while saving desk space, and working across work and personal computers. The reporter's own use case is keeping one PC display as a fixed dashboard that can be updated on the fly while moving among virtual desktops that would normally hide that dashboard. Apple, Asus and Lenovo have developed options that extend a work surface to a tablet; Windows includes support for using another PC as an external display; and Logitech enables the feature with higher-end keyboards or mice.

For a vendor-independent approach, several software-only and hardware options exist, most of which also require software. Many offer "seamless" mode, where the mouse can be dragged from one computer's display to another's, and "hotkey" mode, where a key combination instantly switches cursor control from one PC to another. Hotkey mode can be quicker depending on cursor position, but it can take a moment to reorient to the new position.

Software options offer convenience and expedience, according to TechRadar. As long as the PCs share an internet connection, users can download a program and move the cursor between them. They require no extra desk space or available USB connections. Hardware options are usually limited to two computers, but software bridges can work across more PCs than one would practically have ready. However, these options usually require the computers to be on the same network. As with other peer-to-peer applications over Wi-Fi, they often fail on public networks such as cafes or co-working spaces. If Wi-Fi becomes spotty or unavailable, the connection can slow down or break. Only some options work across platforms, and none work with Chrome OS, TechRadar said. At least four solutions can bridge the gap, it said.

Mouse Without Borders was one of the projects from Microsoft Garage, a skunkworks group focused mostly on mobile apps. It works only on Windows. Although it has not been updated in several years, it still works well, is available in PowerToys, and is one of the simplest apps to set up. After installing it on up to four PCs, the user launches the app and selects the networked PCs to join. The software generates a lengthy passcode to bind them. Once entered, the cursor can move freely between devices. MwB also supports automatic Clipboard sharing between computers, so information can be copied from one computer and moved to its neighbor. This also works with copying and pasting files in Explorer, although files cannot be dragged from one PC to another.

Synergy and DeskFlow have an unusual shared history, TechRadar reported. Synergy began as an open source app 25 years ago before the developer took it commercial through a company now also called Synergy. When forks such as Barrier and Input Leap failed to stay up to date, the company contributed financial and code resources to help develop DeskFlow as an actively maintained open source successor. Both support Windows, Mac and Linux. After installation, one PC is designated as the server and others, typically specified by IP address, are clients. A "grid" user interface on both ends allows the user to specify whether the mouse jumps to the other computer via the left, right, top or bottom edge of the display. Both support TLS encryption and Clipboard sharing. Synergy uses Bonjour network detection to streamline locating other computers on the network and offers more robust enterprise management features.