How do I use this free online compass to find north?

Using OnlineCompass.app is simple and completely free. Just open the website on your phone or browser—no app download needed. Our online compass uses your device’s sensors to show your direction instantly, helping you find true north, south, east, and west in real time. Make sure to allow location access and follow any calibration steps for the most accurate results. Whether you're hiking, traveling, or just curious, this free digital compass is always ready to guide you.

Enabling Sensors

To enable sensors for chrome, open given link (copy and paste) and make Generic Sensor Extra Classes to enable and Generic Sensor feature flag to enable motion sensors on the previous Chrome versions (before Chrome 67). Restart Chrome and you should be good to go.
Link 1:

chrome://flags/#enable-generic-sensor-extra-classes - Click to Copy

Link 2(Required Only for Old Versions Chrome < 67):

chrome://flags/#enable-generic-sensor - Click to Copy

Figure for Reference:

Compass

A compass is an instrument used for navigation and orientation that shows direction relative to the geographic cardinal directions (or points). Usually, a diagram called a compass rose shows the directions north, south, east, and west on the compass face as abbreviated initials. When the compass is used, the rose can be aligned with the corresponding geographic directions; for example, the 'N' mark on the rose points northward. Compasses often display markings for angles in degrees in addition to (or sometimes instead of) the rose. North corresponds to 0°, and the angles increase clockwise, so east is 90° degrees, south is 180°, and west is 270°. These numbers allow the compass to show magnetic North azimuths or true North azimuths or bearings, which are commonly stated in this notation. If magnetic declination between the magnetic North and true North at latitude angle and longitude angle is known, then direction of magnetic North also gives direction of true North.

Is there a compass on my phone?

Does your Android phone have a magnetometer? Yup, chances are that it does as most Android devices do. Even if you have an old or a cheap phone, there's likely a magnetometer inside of it. And, Our website make use of that magnetometer to display a digital compass on your phone's screen.

Which way is north?

You know the sun rises in the east and sets in the west so when you face towards east your left hand tell you north and on your right side is south. If you are in the Southern Hemisphere then it will be the other way round.