Smooch.io for Facebook Messenger - Message your customers from Slack, Front, a bot or anywhere!
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
It's Alive - Create a Facebook bot in minutes
Live Chat by Sumo.com - Instantly communicate with customers, prospects & visitors
GoSquared Live Chat - Beautiful, simple, and free live chat for your website
Sparkcentral - Good old fashioned customer service, delivered in a high tech way