KATWARN is known to be a warning and information system within Germany. In dangerous situations, such as fires, severe weather conditions and the discovery of bombs, it notifies potentially threatened individuals. The system has been active in Germany since 2011 and counts over three million users. By introducing it as a national warning system in Austria, it also gains the opportunity of obtaining warnings internationally. The registration via the smartphone app is free of charge and optional. The app offers warnings for ones current location and is considered as a so called "Schutzengel." One also has the option of selecting two favorite locations, for which one can also receive potential warnings. Security information is also provided for certain events or music festivals if one has subscribed to them. In addition to the app, KATWARN also spreads security warnings via text message, digital ads, public transport schedules, web portals and on-board computers. Aside of the public organisations that use the app (police and fire brigade), certain businesses also make use of the system by applying it as a pure business system. Thereby, they supply their employees, customers and guests with internal security warnings.