France on Tuesday began rolling out its app designed to help warn users if they risk being infected with the coronavirus, although the launch was shadowed by delays.
Governments across the world are launching similar apps to France's StopCovid to warn users if they have recently come into contact with someone who tests positive for COVID-19.
Some see them as a key weapon in the long term fight against the virus although activists also fear its use risks eroding civil liberties.
The French app was available for download on Google Play from the afternoon. The office of France's digital technology minister Cedric O said it would soon be available on Apple's App Store.
The rollout had been awaited from midday and the delay sparked a degree of mockery among social media users in France.
Amid the confusion, an app used by the region of Catalonia in Spain -- Stop Covid 19 CAT -- for a while became the top downloaded app in France, according to analytical service AppAnnie.
It appeared that users in France were mistaking it for the French app.
StopCovid will warn users if they came into contact recently for more than 15 minutes with a person who has been infected with COVID-19.
Responding to privacy concerns about its use, O wrote on Twitter that the app is a "health tool to stop the COVID-19 epidemic".