DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
utterances - A lightweight comments widget built on GitHub issues.
Commento - A fast, bloat-free comments system to foster discussion on your website
IntenseDebate - IntenseDebate's comment system enhances and encourages conversation on your blog or website.
giscus - A comments system powered by GitHub Discussions. Let visitors leave comments and reactions on your website via GitHub!
SolidOpinion - SolidOpinion is a fun, new and dynamic commenting platform.