Compass is a web app written in plain HTML/CSS/JS. It uses [DeviceOrientationEvent](https://developer.mozilla.org/en-US/docs/Web/API/DeviceOrientationEvent) and [geolocation](https://developer.mozilla.org/en-US/docs/Web/API/Geolocation) to show a smartphone's GPS coordinates and polar orientation.
Open [compass.keithirwin.us](https://compass.keithirwin.us/) on a smartphone with a compass. Hold the phone level and it should show your direction.
### Is this accurate?
No, not really. Results may vary. As of this writing, Firefox and Chrome browsers handle the DeviceOrientation spec differently. It's only been tested on Chrome for Android.