Google Duo is the top free Android app already

Just days after it started rolling out, Google's new video calling app Duo has become the top free Android app in the US. Justin Uberti, Duo's technical lead, shared the news in a tweet, where-in he also revealed that the app has been launched worldwide.

To refresh, Duo just requires your phone number to get started, and lets you connect with people in your phone’s contacts list. The app is optimized for poor networks, capable of even switching to audio calling if connectivity is weak.

It was recently revealed that the app will soon start supporting audio-only calling as well.