MacDisplay is described as 'Turn any Mac you already own — even an old iMac — into a true extended second display for your Mac. No dongle, no subscription, no account, no cloud' and is an app in the system & hardware category. There are more than 10 alternatives to MacDisplay for a variety of platforms, including Mac, Windows, Android, iPad and iPhone apps. The best MacDisplay alternative is Spacedesk, which is free. Other great apps like MacDisplay are Side Screen, Tab Display, Deskreen and Duet Display.
Turn your iPad/iPhone or Android tablet or smartphone into a convenient side monitor for your Windows or Mac desktop. iDisplay is a universal app specially optimized for iPad, iPhone, iPod Touch, and Android devices screens.
Germany
EU
Smart devices become monitors by connecting them to a PC via USB! The Convenient Connect TwomonUSB
United Kingdom
MirrorHall creates virtual second monitors over the network using UDP video streaming among Linux desktop or mobile devices. It is optimized for low latency, and is based on gstreamer and GNOME's mutter screen sharing APIs.
Uses local Wi-Fi, Ethernet, or Thunderbolt Bridge to add a Mac, Windows PC, or Android device as extra Mac desktop space, or mirror screens on supported computers. It is free, needs no account, subscription, dongle, or cloud relay, and is for trusted networks.
Taiwan
