Mbin is a Fediverse platform for threaded discussions in the style of Reddit and similar link aggregators. It’s still in early days, so the official Mbin documentation is aimed at techy people ⧉, but hopefully they will create a website for ordinary users soon. Techy people might also want to look at the Mbin source code ⧉. If you just want to see an example of what Mbin looks like, there’s a major server at Fedia.io ⧉ (but please bear in mind I can’t guarantee how reliable this is as the platform is still being worked on).
Wasn’t this called Kbin before?
Mbin is based on an earlier project called Kbin which had a different lead developer. The original Kbin project stopped development, but Mbin carried on and built upon the work of Kbin.