The backend for running half a million apps doesn't look anything like the backend for running a single app. Open-sourcing the actual Parse stack was not an option, and no one would've put in the effort to actually run the dozens of components involved. I started from scratch because that was the only way.

The hosted parse.com service is meant to support hundreds of thousands of apps. It was not really meant to be self-hosted by individual developers serving a couple of applications.

Assuming this is true, probably due to the fact that most apps using Parse are already in Javascript.