Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Freshservice - Freshservice: the one-stop cloud solution for all your IT management needs.
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
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
JivoChat - JivoChat is a live chat that enables you to talk to visitors on your website
Zendesk - Zendesk is a beautiful, lightweight help-desk solution.