By default, GitHub Pages do not have a commenting system, being just static sites.

Many Jekyll-based blogs use Disqus¹. The idea is that each post embeds an iframe that fetches comments from an external site and also provides a comment form. When that form is submitted, the new comment goes again to that external site which stores it.

However, on several sites that use Disqus, I have seen a feature that I very much dislike. They call it Promoted Discovery. Near the comment list, they show a selection of a few posts of your own that are somehow related to the current, and a selection of a few pages by other users. What drives Promoted Discovery is apparently how much the promotee paid to Disqus, and some percentage of that payment goes to the users on whose blogs these ads are displayed.

Excuse me while I go compose an AdBlock Plus element hiding rule for that abomination.

disqus.com###discovery

OK, that was easy. And they actually do not just allow anyone into the program; it’s invite-only. Which means I’m initially ineligible and will have the chance to reject their offer if and when they make it. But still, I do not want to support and endorse a system that does that to its users.

So what do I want from a commenting system?

• It shall not force any advertisement on me or my readers. Preferably, it shall have no advertising program at all. (Yes, I understand they need to make money. Offer paid hosting. Offer advanced features. Offer support. But do not bribe users to display ads.)
• It shall not require registration from commenters. Commenters should be able to log in with their Google, Facebook, Twitter or OpenID accounts. Preferably, that should be the only UI displayed (no account creation dialog after first login).
• It shall authenticate commenters. I don’t want to hear from anonyms, and I don’t want commenters to be able to spoof each other.
• It shall have notifications. Both for me when someone comments on my post, and for the commenters when I or someone else replies to them. Preferably, notifications should be by email.
• It shall support Markdown. I use Markdown for my blog and expect to reply to commenters in the same format. Preferably, it should support the same dialect of Markdown as Jekyll does.
• It shall not lock me in. At any time I should be able to export all comments posted in my blog and to re-import them into another system of my choice.
• It shall be Free. As in speech, according to Stallman’s Four Freedoms. I should be able to deploy my own instance, if need arises, and to modify it as I see fit.
• It shall not bring cruft in. I don’t want to increase my dependence on certain technologies, including, but not limited to: PHP, Perl and MySQL. Ubuntu packages are preferable to PyPI or Cabal packages or Ruby gems.

I have investigated a few options and compiled the following table:

And the only viable solution seems to be Discourse. It has a minor annoyance that it displays an account creation dialog after logging in with Google (and probably other social services), but I expect this can be removed easily.