Isso

Isso – Ich schrei sonst – is a lightweight commenting server written in Python and JavaScript.

CommentLuv

CommentLuv provides plugin that enables readers to post their comments.

Commentar is a self hosted open source commenting system which can easily be integrated into any…

Commentbox is a jsf component that allows quick realization of a comment functionality

Commentics is an advanced PHP comment script with many features.

A fast, bloat-free comments system to foster discussion on your website

Disqus is a global comment system that improves discussion on websites and connects conversations across the web.

Facebook comments plugin lets people comment on content on the site using their Facebook account.

Add modern discussion and social interactions to your website

IntenseDebate’s comment system enhances and encourages conversation on your blog or website.

Easy to set up, ad-free and reliable comment system

LiveRe provides comment management and content response solutions.

Master Comments System is a very compact comments system with basic options:

RbComment - Zend Framework 2 module for drop-in, self-hosted comments, with email notifications…

Remarkbox offers a free comment system to keep readers engaged with your content.

coComment is a service for managing, powering and researching conversations online.

jskomment is an open source commenting system that is built on javascript and AJAX.

talkatv is an open source comment service much like …