Apps similar to TwomonUSB include Spacedesk, which has a free version. Other options are Side Screen, Deskreen, Tab Display and Weylus. You can choose from more than 10 Screen Mirroring Apps like TwomonUSB for Mac, Windows, iPad, Android and iPhone.
GlideX is a cross-device screen-sharing solution. Using wired or wireless connections, you can create a bigger and better work or play space. GlideX optimizes your workflow in the blink of an eye!
Taiwan
Use your iPad as a wireless display, to extend your Mac desktop. Ever wish you had an extra display for your computer? There’s an app for that! With Air Display, you can use your iPad as an additional monitor for your Mac (Windows no longer supported)
United States
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
Make your iPad/tablet/computer into a secondary monitor on Linux. - GitHub - kbumsik/VirtScreen: Make your iPad/tablet/computer into a secondary monitor on Linux.
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.
ItalyEU
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.
