Google's Duo makes mobile-only one-to-one video calling fast and simple

In addition to Allo, Google also introduced a new video calling app called Duo. The app aims to provide mobile-only one-to-one video calling in a simple yet faster way. Google claims that Duo should work fone on even slower internet connection.

Similar to Allo, to get you started with Duo, you'll have to log-in with you phone number, so that you can make video calls with anyone in your contact list. Duo comes with a feature called Knock Knock, which offers a personalized preview of the caller before you answer the call.

The app supports calls in HD video and audio, and is optimized to adjust the quality of video call for slow networks. It can work and switch seamlessly between WiFi and cellular networks. It also offers end-to-end encrypted video calls.

Duo will be available for Android and iOS later this summer.