I'm sure you have to find some free comment services which support widget to embed in our websites. For example this blog, it's includes on static html files, and have to write it's own comments function, that's too overhead!
I have been try disqus, but it doesn't free anymore, the ads from free tier too big and anoying, and this blog too small, so it's not for me.
Utterances the savior
I'm randomly found Utterances when suffering on the internet. And the first impression, that's genius!
But you can not comment as anonymous, but I think that's acceptable. So if you are writing technical blog, I recommend you should give Utterances a try, that was epic!