UseResponse - Open-source, self-hosted customer feedback software, live chat and helpdesk system that you can install on your server. Organize documentation using knowledge base and get feedback from social networks with centralized system

OptinMonster - OptinMonster helps to convert abandoning website visitors into subscribers and 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

OptiMonk - OptiMonk is the most powerful Onsite Retargeting platform, that helps you increase the conversion rate of your site, and get more leads by recovering lost visitors.

ChatWoot - Open-source omnichannel customer engagement platform

POPUPSMART - A no-code tool to increase e-commerce sales, build email lists and engage with your visitors in just 5-minutes.