Duet Display - With Duet Display, you can transform your iPhone or iPad into a second display to expand the screen space of your PC or Mac system.
spacedesk - spacedesk expands the Windows desktop computer screen to other computers over the local area...
iDisplay - iDisplay is an app that turns a mobile device into a secondary desktop monitor. The app currently supports iOS, Android, Windows and MacOS, and it lets users connect a desktop computer to a mobile device over WiFi. Read more about iDisplay.
Samsung DeX - Connect your Galaxy S8/S8+ to a monitor
TwomonUSB - You can create dual monitors quickly and easily using a USB.
Splashtop Wired XDisplay - Use Splashtop Wired XDisplay to turn your iPad, Android tablet, Kindle or smartphone into a high-performance extra monitor for your computer.