Nekofunjatter
When your cat steps on the keyboard, the Flohwalzer plays.
A macOS menu bar app that notices when your cat lands on the keyboard
and plays the Flohwalzer (“The Flea Waltz”) automatically.
Choose piano, 8-bit, or your own custom sound,
and block key input so nothing gets typed by accident.
Features
Four ways to protect your work from your cat
Cat Detection
Detects when several keys are held down at the same time for a set duration. It picks up the telltale pattern of a cat sitting on the keyboard and tells it apart from human typing. The number of keys (1–5) and hold time (0.3–2 s) are fully adjustable.
Choose Your Sound
Piano: the classic Flohwalzer from a real piano recording.
8-bit Style: a retro game take built from square waves (default).
Custom Sound: any audio file you like (mp3, wav, m4a, and more). Your favorite sound effect or voice works too.
Key Blocking
While a cat is detected, key presses are not passed to the app in focus. No more “dddddkjhsd” sneaking into your draft or your code. You can turn this on or off.
Lives in the Menu Bar
It stays out of the Dock and runs from the 🐾 icon in the menu bar. Preview, change settings, or force-stop in one click. A 60-second hard timeout releases everything automatically, even if something hangs.
Requirements
Universal binary for Apple silicon (arm64) and Intel (x86_64)
Required to monitor keys system-wide. When prompted on first launch, allow Nekofunjatter in System Settings → Privacy & Security → Accessibility.
FAQ
Is it free?
Yes, completely free. No ads and no in-app purchases. The source code is on GitHub under the MIT License.
Can I use it without a cat?
Of course. It detects several keys held down at once, so it also reacts when a book lands on the keyboard or you lean on it with your elbow. It makes a fun demo, too.
What can I use as a custom sound?
Any audio file macOS can play (mp3, wav, m4a, and so on). Set a favorite sound effect, your own voice, or your pet’s meow, and it plays every time a cat is detected. Just pick the file from Sound → Choose Custom Sound… in the menu.
macOS says the app “is damaged and can’t be opened”
That is a Gatekeeper warning right after download. For the first launch only, right-click → Open Nekofunjatter.app in Finder. The distributed build is notarized by Apple.
It triggers too often (or not often enough)
Adjust Keys to Trigger (1–5) and Hold Time (0.3–2 s) under Trigger in the menu. You can tune the sensitivity to your cat’s size and habits.
It got stuck while blocking keys
Click the 🐾 icon in the menu bar and choose Stop Now (Unblock Keys). There is also a built-in 60-second hard timeout, so it releases on its own even if you leave it.
Can it start automatically at login?
Yes. Turn on Launch at Login in the menu, and cat protection starts every time you start your Mac.
Is it on the App Store?
The App Store does not allow system-wide key monitoring, so for now it is distributed directly from GitHub Releases. The downloadable .dmg is notarized by Apple.
Download Now
Free and open source. Keep your work safe from your cat.
macOS 13 Ventura or later / Universal Binary