This is one we're heavily considering. We might end up open sourcing only the front-end but keeping the API private. One of the difficult parts is the data to work with it locally. We think that could work by having a staging API that people work with locally that has removed all private information (private notes, non-publicly saved books).

We'd very much like to make this public and allow people to submit pull requests. If anyone would be interested in being an early beta tester of this let us know. When/if we do this we'd like to do it right, and that means having a great initial experience.