FWIW news.ycombinator.com codebase is partially open I think but written in a small Lisp dialect. I think lobste.rs is open source. Edit: it is. Also I though

FWIW news.ycombinator.com codebase is partially open I think but written in a small Lisp dialect. I think lobste.rs is open source. Edit: it is. Also I thought it was written in PHP but it turns out to be Rails.