“Google Duo — a simple 1-to-1 video calling app available for Android and iOS. Duo takes the complexity out of video calling, so that you can be together in the moment wherever you are,” states the official Google statement.
"We built Duo with an emphasis on privacy and security, and all Duo calls are end-to-end encrypted," the company continued in the blog post.
Duo has one unique feature called “knock knock” that sets the app apart from its competitors like FaceTime and Skype. The feature lets the recipient of a call see the caller before they accept and turn on their own camera.
Unveiled at the Google I/O developer conference in Mountain View back in May, Google Duo will be available on the Android and Apple app stores this week.