Lime Talk - Lime Talk is an online application that allows you to easily embed a chat widget onto your site.
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
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
Mibew - The official site of the open-source live support application Mibew Messenger
Crisp Chat - Multi-channel customer support software
Userlike Live Chat - Userlike is free live chat software for website and mobile support.