Talkus - Chat with your website users from Slack
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Chatlio - When you have a business to run, your average instant messaging software just will not do. You need an internal presence upon which your entire team can collaborate on. Read more about Chatlio.
Aircall's Zendesk App - The best phone companion for Zendesk
Drift for Slack - Talk to your website visitors & customers in real-time
Smallchat Beta - Slack integration for chatting with visitors to your website