The SidePane app turns an iPhone Duo into a second display for a Mac, with touch and Apple Pencil input going to the Mac. You drag windows onto the phone like you would with any external monitor, and the picture resizes when you fold or turn the iPhone Duo.
The iPhone app is on the App Store and pairs with a free Mac app that you download separately. Yosei reaches your Mac from anywhere, but SidePane connects over a USB cable or the same Wi-Fi network as the Mac.
The SidePane app adds a Mac display
macOS treats the iPhone as a new monitor named after the device, so you move windows onto it the same way you would with any other display. The Mac display follows whichever screen of the iPhone Duo you use, the inner display or the outer display, and it resizes when you fold or rotate the phone. Each screen keeps its own text size, and the picture stays clear of the rounded corners.
In tent mode, you can stand the iPhone Duo next to your laptop, open a document on the outer display and sign it with an Apple Pencil.
Pencil and touch work on the Mac
Touch and Apple Pencil input go straight to the Mac. You can sign a PDF in Preview and send the signed page back to the Mac, mark up screenshots in any Mac app, or handwrite a note that SidePane types out on the Mac. Swipes work like trackpad gestures for moving through documents and tapping items.
USB reaches 120 frames per second
A USB cable gives the lowest delay and up to 120 frames per second. Wi-Fi tops out at 60 frames per second and needs the iPhone on the same network as the Mac. If you unplug the cable, the session carries on over Wi-Fi with your windows where you left them.
You plug in once and approve the pairing on the Mac, and after that the iPhone connects on its own.
Free for 15 minutes, $9.99 to unlock
The iPhone app and the Mac app are both free, with sessions limited to 15 minutes that you can restart as often as you like. A one-time $9.99 unlock removes the time limit on every iPhone signed in with your Apple Account, and Family Sharing is included. There is no subscription and no account.
The Mac side needs Apple silicon and macOS 15 or later. The Mac app is a direct download from the developer, because the display feature needs a macOS capability that the Mac App Store does not allow, and it asks for Screen Recording and Accessibility permissions.
On the iPhone side, SidePane is 3.1 MB and runs on every iPhone with iOS 18 or later, not only the iPhone Duo. The video stream is not encrypted, so the developer recommends the USB cable over Wi-Fi on public networks.
