Epoch by Postmatic - A native WordPress Disqus alternative with a focus on speed and privacy: 100% realtime native...
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.
LiveFyre - livefyre-subscriptions - A isomorphic JavaScript library for managing Subscriptions in Livefyre's Personalized News Stream service.
Commento - A fast, bloat-free comments system to foster discussion on your website
Muut - The complete discussion system for your site. Forums, commenting and messaging right on your site. Unlimited posts, users and traffic, for free.