A working compass in your browser
Simple, reliable measurement tools powered entirely by your device's sensors.
What we built
Boussole en ligne is a small suite of measurement tools that run as a static site. The compass reads your phone's orientation via the standard DeviceOrientation API. The ruler asks you to calibrate once with a method of your choice. The spirit level reads your device's pitch and roll. The inclinometer measures slope angles. The sun compass and moon position tools complete the suite with real-time astronomical calculations.
Available tools
Each instrument is designed for a specific purpose and runs directly in your browser, with no download or installation required.
Compass
Reads your device's orientation via the DeviceOrientation API. On iPhone and iPad, the browser provides a calibrated heading in degrees from magnetic north.
Ruler
A real-size online ruler for measuring in centimetres and millimetres. A one-time calibration (device profile or screen size) ensures accuracy.
Spirit Level
Checks whether a surface is level by reading your device's tilt sensors in real time.
Inclinometer
Measures the slope angle of a surface in degrees, grade percentage, and rise/run ratio.
Sun Compass
Shows the Sun's direction and altitude in real time based on your geographic position.
Moon Position
Calculates the Moon's position, phase, and illumination in real time.
What we don't do
We don't set analytics cookies. We don't run tracking pixels. We don't have user accounts. Your sensor data never leaves the page — no network requests are made after the initial asset load.
How it is built
Static HTML pages generated by Astro, with canvas rendering and orientation handling in vanilla JavaScript. No backend, no accounts, no telemetry.
Transparency
This site is an independent project. There is no company, no investors, no advertising model. The goal is simple: provide useful measurement tools, accessible to everyone, without compromising your privacy.