Which Markdown editor does Reddit use?

Luc*_*emy 5 javascript markdown reddit npm reactjs

The new redesign of Reddit features a really slick WYSIWYG/Markdown editor. Screenshots:

花哨的裤子

Once clicking on "Switch to markdown":

降价

Is this an open-source library available for implementation, or is this entirely an internal Reddit-only solution?

On another note, I've been comparing a whole bunch of Markdown editors, and can't seem to find anything that works really well with React. SimpleMDE isn't bad, but its last commit was two and a half years ago, and it has no official React bindings either.

What would be my best alternative for direct implementation into a React app?