DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
Epoch by Postmatic - A native WordPress Disqus alternative with a focus on speed and privacy: 100% realtime native...
HashOver - HashOver is a PHP comment system intended as a replacement for services like Disqus.
talkatv - talkatv is an open source comment service much like ...
Joint Comments - An embeddable comment widget for websites, blogs, ecommerce & static pages.
Commento - A fast, bloat-free comments system to foster discussion on your website