Gitalk is a commenting system that can be used as an alternative to Disqus. Gitalk uses the Github issues to track comments.
I found it really nice. I think developers should use something like gitalk instead of disqus because it's open-source, uses github issues to track comments.
Also, if you plan on using gitalk and are building a vue or gridsome app. Here are plugins for you that make adding Gitalk to your app easier.