Google Duo: An Easy Guide to the Best Features Google Duo is a video chat application that was developed by Google and is available on Android and iOS devices. This was first announced in May 2016 along with another software called Allo which is an instant messaging application. The Duo app was launched in the United States in August 2016 and then globally a couple of days later. After its release, Duo climbed to be the number one free application on Google Play, amazingly within two days of its initial release. The app has many great features and this book will seek to cover some of these to ensure the reader is clear on what can be done in this application.