Commento
Commento is a very lightweight commenting engine which I am working on integrating here
The main idea is that it is lightweight and supports OAuth right out of the box. I like that. At the time of writing, all I need to do is include a simple hugo shortcode to get the comments on any page I want. The bundle when minified and gzip’d is only 8.6 kb. The css is a whopping 25.9 kb, and will need a lot of love to get down to near or exactly 0