Google Duo is a new mobile one to one video calling app. Google also announced Allo a new messaging app, which relies on a simple user interface. Google announced both new apps at Google IO 2016 developers event.

Google Tweeted about Google Duo:

When you open the app, a card with big circle images of your contacts will appear. Tap one and that’s it. There is not much in the app interface, it’s a neat, fast and reliable video calling app.

Most notable feature of the app is “Knock Knock”. When someone calls you, you can see a live video preview of them without attending the call. Duo is a video companion to Allo which will be available later this summer.