Skype is an instant messaging and VOIP (Voice Over Internet Protocol) client to communicate with people in a distant place.

ooVoo is a video chat and an instant messaging client.

SightCall remote support software enables live video streaming and remote access on mobile devices and desktops for customer service and tech support.

Viber Free Messenger and Phone Calls.

Google Duo is a video chat mobile app available on the Android and iOS operating systems.