1. Akismet is a spam fighting service that protects millions of WordPress sites from comment and contact form spam.

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

  3. livefyre-subscriptions - A isomorphic JavaScript library for managing Subscriptions in Livefyre's Personalized News Stream service.

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