It's super scary, especially because ForeFlight has no realistic competition.

I've had this off-again, on-again plan (more like dream) to write an open-source ForeFlight clone, as I used to write aviation mapping software for a living and could probably throw something passable together. But the application's sheer quantity of high quality features makes the project super-daunting. It's unrealistic to believe that a group of amateurs without a budget could even come close to replicating it.