Germany has largely got it's coronavirus infections control and now it's government is telling citizens to down a smartphone app to keep it that way.
It launched its new contact-tracing app on Tuesday for Apple and Android devices.
Like some other tracing apps it uses your phone's Bluetooth to measure close contacts between people and issues a warning if one of them later tests positive.
Helge Braun is the head of the German Chancellery.
"This is not the world's first corona app but I am pretty confident it is the world's best. To download and use it is a small step for every one of us but a big step in the fight against the pandemic."
The app has mixed public opinion and in April the project nearly went off the rails. Berlin had to abandon its initial approach to the software on concerns the data was stored on a central server, which privacy experts said could allow people's relationships to be spied on
Germany joins Italy, Poland and Latvia in launching apps based on technology from Apple and Alphabet's Google that, they say, preserves privacy by logging Bluetooth contacts on the devices themselves.
In news coinciding with the German launch, European Union members agreed technical standards for national apps to 'talk' to each other.
A step towards making it possible to trace infections across borders as the peak summer tourist season approaches.