DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
Commento - A fast, bloat-free comments system to foster discussion on your website
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.
utterances - A lightweight comments widget built on GitHub issues.
Cusdis - Open-source, lightweight comment system for your website
giscus - A comments system powered by GitHub Discussions. Let visitors leave comments and reactions on your website via GitHub!