Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Drift - A messaging app that helps you grow your business.
Live Chat by Sumo.com - Instantly communicate with customers, prospects & visitors
Talkus - Chat with your website users from Slack
GoSquared Live Chat - Beautiful, simple, and free live chat for your website
HeyHi.sg - Video call with interactive whiteboard