Flightradar24 began in 2006 when two Swedish aviation enthusiasts in Stockholm fed ADS-B receivers into a web map. It grew into a volunteer network of tens of thousands of ground stations, and today it plots almost every tracked aircraft on Earth in real time.

The interface rests on one decision: a quiet warm-grey roadmap base, yellow aircraft glyphs scattered across it, and dense white panels that open when you click one. The chrome is light, the type is plain Open Sans, and yellow is kept for the aircraft and the primary button so nothing else competes with the traffic.