Duet Display is an app designed to get you some extra use out of your iPad.
Instead of letting your iPad collect dust when you're not using it, Duet Display turns your iPad into a second display for your Mac, using the iPad's charging cord to connect to your computer.
The app was created by Rahul Dewan, an engineer who worked at Apple for three years on the iPad and iMac.
"A second display can increase productivity up to 48%," Dewan told Business Insider. "If you have an iPad, you already have that second screen. With Duet, you can finally use it. Otherwise, your $700 device is just sitting there."
In addition to giving you extra screen real estate (which is great for musicians, designers, and photo and video editors), Duet Display also takes advantage of the iPad's touch capabilities, allowing you to tap and scroll through whatever you choose to drag over to the second display.
While other apps like Air Display already exist that will turn your iPad into a second display, those apps connect your iPad to your Mac using wi-fi, which leads to a lot of lag. Duet Display, on the other hand, has zero lag, and it also offers a true Retina resolution that takes full advantage of the iPad's HD display.
Duet Display also offers energy saving options for people using older Macs that aren't as powerful. You can choose between regular and Retina resolution (you'll need a newer Mac for Retina mode to work seamlessly), but you can also switch between a 30 Hz and 60 Hz refresh rate.
Setting up Duet Display is a cinch. You just download the app on your iPad and for your Mac, restart your computer, and you're ready to go.
Because my work computer is a Mac Mini, I stuck to the regular resolution along with a 60 Hz refresh rate, and it worked well without any hiccups. While the Retina resolution certainly makes everything crisper, it also puts more work on your computer, but if you have a more recent Mac you should be all set. In use, Duet Display performed exactly how I'd like it to. I could drag a webpage with my Twitter feed or Slack over to my iPad's screen, and you can tap fullscreen to have whatever window you're displaying expand to fill the entire screen. YouTube videos played back smoothly, and I even played a game of Hearthstone just to see if it worked for games (it does, but most of the time it makes more sense to just game on your primary display).
Duet Display also works in either portrait or landscape mode.
Another bonus feature is that you can technically use Duet Display to turn your iPad into your only display, though that feature only works if you disable your Mac login, since Duet Display only works after you've logged in). Most importantly, Duet Display is the first app that actually turns your iPad into a second display I'd actually like to use. As someone who has tried Air Display and uninstalled it shortly afterward, frustrated, I can honestly say this is the only option that's worth it.
You can download Duet Display by clicking here.
