Plottable.js is the only charting package I've used that's a real library, not just a set of pre-canned charts. Sadly, the devs don't seem to have a lot of time

Plottable.js is the only charting package I've used that's a real library, not just a set of pre-canned charts. Sadly, the devs don't seem to have a lot of time to devote to updating the site.