Messenger Video Calls - Facebook Messenger, now with HD video calls
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Live Chat by Sumo.com - Instantly communicate with customers, prospects & visitors
CallKite - Your website’s video call center in just one click.
Zendesk for Startups - Everything you need for seamless customer conversations.