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.

VECA - Your eCommerce assistant

Zendesk - Zendesk is a beautiful, lightweight help-desk solution.

Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community

Slack with your Users - Speak to your app's users entirely within Slack