Flightradar24 tracks positions of aircraft in real-time and turn that data into engaging consumer and business applications. The data comes primarily from a proprietary, crowd-sourced network of 30,000+ so-called ADS-B receivers hosted by private individuals and companies all over the world and tracks 180,000+ flights per day. This network of ADS-B receivers is the largest in the world.
In addition to ADS-B data, Flightradar24 is able to get positional data for non-ADS-B equipped aircraft through the use of Multilateration (MLAT). The ADS-B and MLAT data is merged with schedule and flight status data from airlines and airports to create a unique flight tracking experience. You can read more about how Flightradar24 works here:
http://www.flightradar24.com/how-it-works
Each day Flightradar24 has over 2 million unique users and our app has been the #1 selling app overall in Apple’s App Store in over 130 countries. Most airlines and many other companies in the aviation industry (including Airbus, Boeing and Embraer) use our services.