Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Crisp Chat - Multi-channel customer support software
tawk.to - tawk.to is a free live chat app that lets you monitor and chat with visitors on your website or from a free customizable page
Mutiny - Personalize your website for each visitor
JivoChat - JivoChat is a live chat that enables you to talk to visitors on your website
HappyFox Chat - HappyFox Chat is a live chat software for the websites.