Senso: Level, Lux, dB, Compass

Senso turns your phone into a pocket workshop of precision instruments. Five sensor tools, zero clutter, no in-app purchases, no PRO tier — every feature is free, forever.

▪ BUBBLE LEVEL & PROTRACTOR
A 1D bubble bar plus a 2D bullseye target for laying shelves, hanging frames, levelling a tripod, or checking a worktable. Snap-to-zero filtering kills jitter, haptic feedback pulses the moment you cross into the green band. Includes a digital protractor with degrees, percent, n/12 roof pitch, and radians, plus a slope calculator with accessibility hints (wheelchair ramps, residential roofs, drainage gradients).

▪ LUX METER (LIGHT METER)
Read ambient illumination in lux with a background that gradients from black at night to bright white at noon. Plant mode covers Monstera, Ficus, Peace Lily, Phalaenopsis, ZZ, Cactus and Pothos with min / ideal / max ranges. Workspace mode flags whether your office, reading nook, kitchen, sewing area, kids' study or workshop meets ISO / DSTU minimums. Reference sheet walks you from moonlight to direct sunlight.

▪ DECIBEL METER (SOUND METER, dB / SPL METER)
A vertical VU meter with a peak indicator, central dB readout, and a 60-second sparkline. A-weighted (dBA) measurement with the IEC 61672 IIR cascade for a true SPL feel. NIOSH 3 dB exchange-rate hearing-safety calculator shows remaining safe exposure at the current level — useful at concerts, construction sites, factories, restaurants, or noisy commutes.

▪ COMPASS WITH TRUE NORTH
Animated compass rose with cardinal labels and 5° tick rings. Switch between magnetic and true north — declination computed locally with the full WMM-2025 spherical-harmonic model (no internet required). Set-bearing chip lets you lock a target direction. Magnetic-interference warning kicks in near speakers, motors, or large metal objects.

▪ HISTORY
Save any reading from any tool with a single tap. SQLite-backed log with per-feature filters (Level / Light / Sound / Compass) and bulk-clear.

▪ WHY SENSO
- 100% free, no PRO tier, no in-app purchases, no paywalls, no trials.
- Works fully offline. All sensor processing is on-device.
- Privacy-first: Senso collects nothing. No accounts, no tracking, no analytics. Ads are served by Google AdMob (industry standard).
- Material 3 design with light + dark themes that follow your system.
- Eight languages: English, Ukrainian, Polish, German, Spanish, Portuguese, French, Italian.
- Calibration shortcuts for level, microphone, and compass.
- Optional camera mode for the bubble level — overlay a virtual horizon on your camera preview.

Senso runs on devices with the standard Android sensor suite (accelerometer, microphone, magnetometer where available, ambient light sensor where available). The true-north compass uses your location, but only while you have the Compass screen open — never in the background, never stored, never sent off-device.

Smart sensors in your pocket — that's it.