DISQUS - Disqus is a global comment system that improves discussion on websites and connects conversations across the web.
Kamon.io - Kamon makes an instrumentation library and Application Performance Monitoring tool that helps developers find and fix performance issues in microservices. Works best for Scala (Akka, Play, Lagom) and Java.
Commento - A fast, bloat-free comments system to foster discussion on your website
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.
utterances - A lightweight comments widget built on GitHub issues.
Wrike - Wrike is a flexible, scalable, and easy-to-use collaborative work management software that helps high-performance teams organize and accomplish their work. Try it now.