What forum software is this?

What forum software powers this message board? I’m curious as it seems pretty sleek, but I can’t find any footers advertising the package creator. They usually say like “powered by…”

This forum is running on Discourse (http://www.discourse.org/). It’s open source software (you can self-host it or pay them to host it for you). It is really nice. The only real complaint I have is that it uses a lot of RAM. I had to upgrade my server instance from 1 GB RAM to 2 GB because it kept running out and started to swap (which it still does sometimes actually).