Sense the impact
A narrowly scoped, user-approved helper reads accelerometer and gyroscope reports from the AppleSPU motion sensor.
A macOS utility with questionable physical inputs
Tap your Mac.
Move through Spaces.
Slap/top listens to your Mac’s motion sensor and turns display taps into Mission Control actions. Left switches left. Right switches right. Top launches Mission Control. Or teach it your own tap and knock patterns. Yes, really.
01 / THE GESTURE
A tiny tap is all it takes.
This browser edition of Slap/top’s LaptopTapAnimationView demonstrates its direct Spaces and Mission Control mappings.
Tap left to switch left. Tap right to switch right. Tap the top edge to launch Mission Control.
Space 5 of 9 · tap any side
02 / UNDER THE PALM REST
Motion in. Spaces out.
Slap/top keeps the pipeline deliberately small. The sensor helper only reads motion reports; it contains no file or network access logic.
Classify the side
Three taps per edge teach Slap/top your Mac and your touch. Adjustable sensitivity and repeat timing keep the gesture intentional.
Switch the Space
Slap/top sends the Mission Control and Spaces shortcuts configured on your Mac. If you changed the system defaults, you can remap each tap direction to match.
LEFT-SIDE TAP
← CONTROL–LEFT
RIGHT-SIDE TAP
CONTROL–RIGHT →
TOP-EDGE TAP
CONTROL–UP ↑
03 / TEACH YOUR OWN GESTURE
Your Mac can learn
Your Mac can learn
a knock code.
Beyond the three screen-edge taps, Slap/top can recognize a custom series of taps or knocks anywhere on your computer—then turn it into an action you choose.
CUSTOM PATTERN / EXAMPLE
READY
Perform it three times
Give the gesture a name, choose how many impacts it contains, then repeat it naturally three times. Slap/top learns both its motion signature and its rhythm.
Choose what it does
Assign the learned pattern to any keyboard shortcut—including your remapped system shortcuts—or have it type a saved text snippet.
Tune the tempo
Adjust the minimum interval as low as 100 milliseconds for quick knock codes. The default remains a deliberate 333 milliseconds between recognized impacts.
Private by design. Learned patterns and their assigned actions stay on your Mac. Slap/top has no account, analytics, advertising, or motion-data upload.
04 / Slap/top, CIRCA 2005
Slap/top hit the forums.
Slap/top hit the forums.
Then the drives spoke up.
2005
A forum-born experiment
Kalani Helekunihi built the original Slap/top and shared it across macOS forums using the name projectle. It was a mischievous little experiment in turning physical motion into a software input.
UH-OH
The hard-drive problem
User reports revealed a serious flaw: on a Mac with a spinning hard drive, a tap could look like a drop. The sudden-motion protection would park the drive heads—and repeated interruptions could lead to data corruption.
“As it turns out, hitting a laptop with a hard drive kills your data.”
OFFLINE
The responsible move was to pull it
Slap/top came down. When copies appeared under other names, Kalani contacted their authors about the same data-loss risk; they took those versions down too.
2026
New silicon. No spinning platters.
Two decades later, SSDs removed the head-parking failure mode that ended the original experiment. Slap/top returns as a native SwiftUI menu-bar app for modern Apple-silicon MacBooks.
A VERY SPECIFIC KIND OF PROGRESS
This is still a laptop. Be nice to it.
Slap/top is designed for light display taps on supported Apple Silicon Macs with integrated screens and SSD storage—not impacts, drops, or vintage Macs with spinning drives. Calibrate gently.
PUBLIC & OPEN SOURCE
Open source,
Open source,
with the whole strange story intact.
Slap/top is completely free and open source under the MIT License. The code, implementation notes, and the whole strange story live together in the public repository.
View Slap/top on GitHubWhat it needs
- Hardware
- Apple Silicon Mac with an integrated screen
- Sensor compatibility
- Any Apple Silicon device with an integrated screen. MacBook, MacBook Air, MacBook Neo, MacBook Pro, iMac
- System
- macOS 14 or later
- Permissions
- Background Item approval
- Price
- Free—no purchase, subscription, or in-app purchase
- Distribution
- Direct download now; Mac App Store build in preparation