There is no API, and unless a lot of people ask for it I'm not planning to build it any time soon either. Making an API isn't too hard, but providing a stable API would slow down development quite a bit as this project is really still in its early days. I don't think it's worth it right now. Sorry :-(

Better data export facilities is something that I intend to do soon-ish, and you could build your own UI with that, but it'll be based on data/DB sync rather than querying an API, which is quite a different workflow.