TouchDown

Use a USB touchscreen with your Mac: tap to click, swipe to scroll, pinch to zoom. If a touchscreen works on Windows, it should work with TouchDown.

TouchDown is a fork of Touch Up by Sebastian Hueber (RWTH Aachen). It fixes screens that Touch Up detects but that don't respond to touch, and adds calibration.

Install

1. Download TouchDown.app from the latest release and move it to your Applications folder.
2. Open it. TouchDown isn't signed by Apple, so macOS blocks the first launch. Go to System Settings → Privacy & Security, scroll down and click Open Anyway. On macOS 14 and earlier you can also right-click the app and choose Open.
3. When asked, turn TouchDown on in System Settings → Privacy & Security → Accessibility. Then quit TouchDown from its menu bar icon and open it again.
4. Plug in your touchscreen and touch it.

Requires macOS 12 or later. To start TouchDown automatically, add it under System Settings → General → Login Items.

Using it

• Tap to click; rest one finger and tap with a second to right-click
• Swipe to scroll, rest your finger, then move to drag
• Pinch to zoom

TouchDown lives in the menu bar. Under Settings you can change these gestures and, for each connected touchscreen:

• choose which display it controls
• Test it: circles show where the screen reports your fingers
• Calibrate it, if touches land beside your finger: touch and hold five targets, try the result, then save

Settings stay with the touchscreen, even if you plug it into a different USB port.

Troubleshooting

The screen shows up in Settings, but touching does nothing. Open Test and touch the screen.

• Circles appear: TouchDown is getting touches but isn't allowed to control the pointer. In Accessibility settings, switch TouchDown off and on, then reopen it.
• No circles: unplug the screen, plug it back in and try again. If that doesn't help, please report it.

macOS keeps asking for Accessibility, even though it's switched on. macOS has kept a permission for an older copy of the app. Quit TouchDown, run this in Terminal, then open TouchDown and allow access again:

tccutil reset All io.github.loopydev.TouchDown

Every touch clicks twice, or the pointer jumps around. Make sure only one copy is running, and that Touch Up isn't running alongside TouchDown.

Touches land a little beside your finger. Use Calibrate in Settings.

The screen isn't listed in Settings at all. It may not identify itself as a standard touchscreen. Please report it.

Reporting a screen that doesn't work

Open an issue with:

• the touchscreen's make and model, and the name shown in TouchDown's Settings
• your macOS version and Mac model
• what you tried from Troubleshooting, and whether circles appear in Test

Building from source

You need Xcode. To build, install to /Applications and launch:

scripts/install-local.sh

Each build is signed ad-hoc, which macOS treats as a new app, so you'll be asked for Accessibility again after every rebuild. To avoid that, sign with a certificate from your keychain, such as the free Apple Development certificate Xcode creates for your Apple ID:

SIGN_IDENTITY="Apple Development" scripts/install-local.sh

Using the touch data in your own app

The touch handling lives in the TouchUpCore framework, which you can embed in your own Mac app to get live multitouch data from any touchscreen: for games, research or prototypes. See TouchUpCore/README.md for a short example. It keeps its original name and API, so code written for Touch Up's framework works unchanged.

License

MIT, like Touch Up. See LICENSE.