SlapDroid: A Slap-Tracking Android App

Overview An Android app with one deliberately absurd purpose: slap your phone, hear a random sound reaction, and watch your slap count climb a global leaderboard. No login, no ads, no real utility, just a fast, fun build meant to spread on its own weirdness.

The Challenge The core mechanic sounds simple, "detect a slap", but phones don't have a slap sensor. The real problem was turning raw accelerometer data into something that reliably reads as "the user just hit their phone" without false triggers from normal handling, walking, or setting the phone down.

Approach Built on Capacitor, bridging the accelerometer into native functionality from a Next.js frontend. Calibrated slap-detection sensitivity by testing across multiple devices, what registered clearly as a slap on one phone barely triggered on another, so thresholds had to account for real hardware variance, not just a single test device.

What Made It Hard Two things ate more time than expected: the Capacitor-to-native accelerometer bridge itself, and per-device calibration. Beyond the core mechanic, the app ended up needing 50+ distinct sound variations and a tap fallback for devices where slap-detection wasn't reliable enough on its own.

Outcome A fully working app: real-time slap detection, instant sound feedback, a global leaderboard, and a landing page with animated visuals matching the app's playful tone. No ads, no accounts, nothing standing between opening the app and slapping your phone.

Stack Next.js, Capacitor, native accelerometer APIs, custom animation for the landing page.