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

Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.

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

Live Chat by Sumo.com - Instantly communicate with customers, prospects & visitors

HelpScout - Help Scout is a simple, straightforward way to provide excellent support

Zendesk for Startups - Everything you need for seamless customer conversations.