The German government's coronavirus warning app has gone live.
The app uses Bluetooth technology and is designed to measure whether cell phone users have breached a 2-meter proximity for a long period of time, reports the CNN.
If a user has tested positive and shared that information with the app, it will inform other users nearby of their diagnosis.
But for the app to succeed, Germany's government will have to overcome a widespread reluctance to share data with authorities.
The country has not made using the app mandatory for its citizens.
Officials have also said that contact information will not be shared centrally, a point of concern for Germans with privacy concerns over the technology.