Answerbase - Add a Q&A system to your website in just minutes, with Answerbase's powerful question and answer software for online communities and customer support.
DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
Smarty Bot - Wiki for tech teams, right where work happens
Question2Answer - A Q&A site helps an online community to share knowledge.
utterances - A lightweight comments widget built on GitHub issues.
Contentful - You don't need another CMS. You need a better way to manage content — unified, structured, and ready to deploy to any digital channel.