Who we are
Get Online Compass is a small independent project, not a company with a sales team. It is built and maintained by developers who spend their weekends outdoors and their weekdays caring rather too much about page weight. The site exists because we kept hitting the same wall of needing a compass for thirty seconds, and when you search for one, you land on a page that wants an install, an account and your location before it will point anywhere.
Every modern phone already has a magnetometer, an accelerometer and a GPS receiver. The instrument is in your hand. All that was missing was a page that reads those sensors honestly and then gets out of the way. That was the whole point of what we set out to build.
What we believe
Free means free
There is no paid tier, no trial period and no feature held back for an upgrade prompt. Whether it is magnetic declination, true north, calibration, the plumb mode, or the sun and moon calculations, all of it is available to everyone who opens the page, for personal or commercial use, with no cap on how often you use it.
Sensor data belongs to you
Your heading, your tilt angle and your coordinates never leave the browser. This is not a policy promise so much as an architectural fact: the tools do their maths on your device, so there is no server holding the numbers, and nothing to leak, sell or share. Settings you choose (a saved calibration, your theme preference) live in your browser's own local storage and go away when you clear it.
An instrument should work when the signal doesn't
A compass that needs four bars is not much use on a ridge or in a basement car park. Every tool here is cached by a service worker the first time you load it, so it keeps working with no connection at all. Add it to your home screen and it opens full-screen like a native app. Only two things genuinely need the network: the reverse-lookup that turns your coordinates into a city name, and the first load itself.
How it works under the hood
The site is built with Astro and Tailwind CSS, and ships almost no JavaScript beyond the code that drives each instrument. The readings come from web APIs your browser already supports:
- DeviceOrientationEvent: the fused compass heading that drives the dial, including Safari's
webkitCompassHeadingon iPhone. - GravitySensor, Accelerometer and DeviceMotionEvent: the gravity vector behind the spirit level's roll and pitch.
- Geolocation API: coordinates and altitude, requested only when a tool actually needs them and only after you allow it.
Magnetic declination, the gap between the north your sensor reads and the north your map is drawn around, comes from the World Magnetic Model, evaluated in the browser for your coordinates and the current date. Sun and moon figures are computed from the standard astronomical algorithms in the tradition of Jean Meeus, again entirely client-side. None of these calculations involve a round trip to us.
Why browser tools instead of an app
A native app and this page read the identical chip, so there is no accuracy advantage of installing one. What differs is everything around the measurement. An app costs storage, asks for permissions it rarely needs, and on the free tier is usually paid for with ads or an upgrade prompt arriving at the exact moment you wanted a reading. A web tool opens instantly, updates without a store review, and runs on whichever phone is nearest rather than the one platform it was written for.
The honest trade-off is that a browser cannot touch a motion sensor until you grant permission, and it needs an HTTPS connection the first time. After that first load it behaves like anything you installed.
Accuracy and limits
On a calibrated modern smartphone the compass typically reads within 2 to 5°, about what a handheld baseplate compass gives you, and the spirit level resolves a few tenths of a degree once zeroed. Both are affected by their surroundings: magnets, speakers, metal desks and car dashboards bend the magnetic field, and a raised camera bump or a vibrating appliance skews a tilt reading.
These are useful, genuinely accurate instruments for everyday navigation, DIY and orientation. They are not certified survey equipment, and they should not be your only means of navigation where a wrong answer carries real risk. Carry a baseplate compass and a paper map in the backcountry, and treat these tools as the excellent second opinion they are.
Get in touch
We like hearing from people who use these tools: a bug report, a feature you wish existed, a device that behaves strangely, or just a note that the compass helped you find your way. Reach us through the contact page. If you are curious about what we do and don't store, the privacy policy spells it out in plain language.
Ready to use something? Start with the online compass, or try the spirit level, sun position and moon position tools.