Online Compass, for When Your Phone Is the Compass

Field notes

The site separates magnetic north from true north and explains that the difference varies by location. Its workflow depends on the phone’s built-in magnetometer, browser sensor permissions, and a reasonably interference-free environment; the page specifically warns about magnets, speakers, laptops, cars, and steel. It also describes a figure-eight calibration gesture and says optional latitude and longitude are calculated locally rather than uploaded.