indemandly - Live chat 2.0: Customer messaging that converts
Conversity - Easiest way to manage Facebook Messenger chats
Message Me - Website to create your contact business card
Slack with your Users - Speak to your app's users entirely within Slack
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Talkus - Chat with your website users from Slack