romanzolotarev.com is a Fediverse instance that uses the ActivityPub protocol. In other words, users at this host can communicate with people that use software like Mastodon, Pleroma, Friendica, etc. all around the world.
This server runs the snac software and there is no automatic sign-up process.
Given #snac's low bar requirements, I think any modern web browser is fine. I use Firefox, but totally agree on the heavy side (I have an unresolved love+hate relation with Firefox). I don't recommend any Chrome-based solution, because Google (though snac works great there).
I wish a small web browser (even a text-mode one!) with support for summary / details existed. In fact, if I ever develop another web app (a case that is probably not going to happen), I would not rely on this functionality.