Eight measuring instruments Android does not ship with, in one app of about a megabyte and a half, with no network permission at all.
No ads. No trackers. No analytics. One permission, the microphone, asked for when you open the sound level meter or the tuner and never before.
A phone carries a gravity sensor, a magnetometer, a barometer, a light sensor and a microphone. Android exposes none of them to you. The apps that fill the gap are mostly a banner ad with a bubble drawn on top.
Nonius is the other kind: every face is drawn as an instrument rather than assembled out of stock components, every reading that depends on hardware has a calibration you can set, and nothing is stored beyond the six numbers that calibrate this one device.
| Tool | Reads | Sensor | Notes |
|---|---|---|---|
| Level | pitch and roll | gravity | round vial and tube, zero point per device, degrees, percent or mm/m |
| Compass | heading and field | rotation vector, magnetometer | the same face doubles as a metal detector |
| Ruler | millimetres, inches | none | calibrated against a bank card, not against the panel's own claim |
| Sound level | dB(Z) | microphone | asks for the unprocessed source so gain control cannot rewrite the number |
| Tuner | pitch and cents | microphone | YIN detection, concert pitch adjustable from 415 to 466 Hz |
| Counter | a tally | none | tap anywhere, survives being closed |
| Altimeter | height and weather | barometer | height above a mark you set, which is exact enough to measure a staircase |
| Light meter | lux | light sensor | six decades, from moonlight to direct sun |
Tools whose sensor the device does not have are shown greyed out with the reason, rather than opening and then apologising.
No dependency injection framework, no navigation library, no HTTP client, no image loader, no font file, no database. Compose, the activity, and the lifecycle bridge for collecting sensor flows. That is the whole dependency list, and the release APK is about 1.5 MiB.
Requirements: JDK 21, Android SDK 36, Gradle (wrapper included).
git clone https://github.com/john-athan/nonius
cd nonius
./gradlew assembleDebug
# APK: app/build/outputs/apk/debug/app-debug.apkChecks, the same ones CI runs:
tools/check.shapp/src/main/kotlin/dev/kaleve/nonius/
core/ the arithmetic, plain Kotlin, no Android import, unit tested
sensor/ sensors and the microphone as flows
data/ six settings on SharedPreferences
ui/ palette, type, the kit every instrument is drawn from
tools/ one file per instrument
Tools.kt the registry: a ninth instrument is a file and a line here
Everything in core/ runs on the JVM without a device and without Robolectric,
which is why the tilt maths, the barometric formula, the pitch detection and the
decibel arithmetic have tests and the drawing does not.
GPL-3.0-or-later, full text in LICENSE. The libraries inside the APK are all
Apache-2.0 and their notice is readable offline in the app under Licences.