I wrote mogade, which is a leaderboard/achievement/stats service. It's open source (https://github.com/mogade/mogade-server https://github.com/mogade/mogade-ser

I wrote mogade, which is a leaderboard/achievement/stats service. It's open source (https://github.com/mogade/mogade-server https://github.com/mogade/mogade-server) and hosted. I don't know of anyone hosting their own; everyone uses mogade.com (maybe because it's free). As you say, building something with the basic features of Parse is trivial. And, if you tailor it to your app, you can get a much cleaner API and better performance. I've wondered how parse will scale as long as it allows ad-hoc queries on unstructured data. FWIW, I wrote the WP7 Parse library, just to get familiar with the service. I'd be game for writing an open source implementation using ruby or node.js, I just wonder if there's really any market for that. It seems to me that if you want to go through the trouble of hosting it yourself, you'll spend the week or so to build your own. Otherwise, you'll use Parse.