Would be nice to have an option to display the AST as a formatted S-expression IMO.

nice user interface - how do you wrap pyhton's grammar in the browser ?

Hey, thanks! There's actually a lot of the stock react-create-app CSS in there.

As for the parsing, it's done on the back-end, front simply fetches an AST every time input changes.

ok, thanks, i was asking since i was playing with simple ASTs myself here http://embeddednodejs.com/compiler/