A Compass App That Actually Admits When It Is Lying
You know that feeling when you are halfway up a trail you have never walked, the GPS has decided to have a moment, and you open your phone compass to re-orient yourself. The needle looks calm. It says that way. You walk for twenty minutes. You come out of the trees and the sun is on the wrong shoulder.
That is the afternoon that made me build NorthPin — a free offline compass for Android and iOS that tells you when not to trust it. Download on Google Play: https://play.google.com/store/apps/details?id=com.tomas.northpin_compass
The problem with phone compasses is that they lie confidently.
Phones use a magnetometer, which reads the Earth's magnetic field. That field is astonishingly gentle at the surface — weaker than a fridge magnet by a factor of a thousand. Anything metallic or electric within reach of your phone can overwhelm it. Car dashboards. Laptop speakers. Magnetic case clasps. Most compass apps treat that sensor as a reliable oracle. It is not one.
NorthPin treats confidence as a feature.
It shows you a heading like any compass. It also shows you the total field strength in microteslas, and whenever that number drifts outside the range Earth's field actually has (roughly 25 to 65 µT), the app flags the reading as unreliable and tells you why. Walk away from the metal. Put the phone down on something non-magnetic. Try again.
True North with proper declination.
The Earth's magnetic pole is not the geographic North Pole. Where I live in Central Europe, the gap is a few degrees. In the western United States it can be more than fifteen. NorthPin looks up the World Magnetic Model for your location and quietly corrects the heading. You see geographic north, not a wandering magnetic ghost inside the planet.
Pin Direction is the feature I actually use.
You aim the phone at a distant landmark, tap once, and the app locks that bearing. As you walk, it shows your drift from the pinned direction in real time. In open terrain or low visibility this is transformative. You can walk straight toward something you cannot see anymore.It shows you a heading like any compass. It also shows you the total field strength in microteslas, and whenever that number drifts outside the range Earth's field actually has (roughly 25 to 65 µT), the app flags the reading as unreliable and tells you why. Walk away from the metal. Put the phone down on something non-magnetic. Try again.
Privacy is not a marketing line here.
No ads. No tracking. No analytics. No account. No internet access. The whole thing is twenty-one megabytes. The sensors only run while the app is open. Location permission is optional and used purely for declination — nothing leaves your phone. You can fly to a region with no signal and it still works, because there is nothing it needs to reach out to.
A tiny indie studio in the Czech Republic built this.
I run Lapnito ( https://lapnito.cz ) — a one-person-plus-friends mobile studio making privacy-first utility apps. NorthPin is the fourth app I have shipped this year. They are all built on the same principles: no ads, no tracking, no account, offline where possible.True North with proper declination.
Try it:
Android: https://play.google.com/store/apps/details?id=com.tomas.northpin_compass
iOS: https://apps.apple.com/us/app/northpin-true-north-compass/id6759560694
Website: https://lapnito.cz
If you take it into the field and it does something strange, email me at [email protected]. A compass that admits when it is wrong needs a maker who does too.