Wondeding if Acha will be open sourced :) Only because their platform description sounds tempting. They say no AJAX once it's loaded (isomorphic) but I don't see that on the site, wondering if that's just not live.
It will be open sourced.
We download whole database at beginning and put it to datascript (https://github.com/tonsky/datascript). We don't make any additional requests to render user/repo profile.
This is a really fun competition and it really highlights how friendly and light hearted the community can be, while showcasing how easy it is to be productive in clojure. Can't wait for next year!