Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Shopify Ping - Chat with customers & get help with marketing in one app
Zopim - Live chat is a faster and more personal way for you to engage your customers. Free for 14 days. No credit card required.
ChatPirate - Offer help and capture leads with a truly simple live chat.
Crisp Chat - Multi-channel customer support software
Drift - A messaging app that helps you grow your business.