live magnetometer scope · find magnets · power cables · speakers · earth field baseline · mobile only · runs locally
device support
why this matters
- earth’s field is around 25–65 μT depending on latitude and altitude. anything noticeably above that is local.
- magspoof and friends: short-range magnetic data injection has been shown to spoof credit-card readers and trigger maglev sensors. the same hardware that reads the field can sense it.
- indoor positioning systems use magnetic anomalies — caused by steel beams in buildings — as a unique fingerprint for each square metre.
- privacy note: web magnetometer access is permission-gated on android and unavailable on ios — both browsers learnt the lesson early.