Cusdis - Open-source, lightweight comment system for your website

Comments by Highlight - Collaboration on Highlight makes debugging faster than ever

Commenze - Fully customizable comment sections for any website

Eccco - Record a listen short audios, like Twitter but with voice.

CommentBox.io - Imagine a cleaner, prettier Disqus, but without the ads, tracking, or sharing of personal data.

Email Comments - Add Google Docs like comments to Gmail