It's a simple self hosted comment system, build in Python and just use sqlite database. By default it only support single website but with some configuration you can also use it for multiple websites.

This post however, not much about Isso but how do I found it.

I was reading Luke Plant's blog and then noticed his comment form a little bit, different.

It triggered the curiousity inside me so I "view source" it using the browser Inspect function.

The word isso definitely stand out, so I googled it (isso comments). The rest is history.