Snow is a place to share Scheme programs, libraries and data. Currently we host only R7RS libraries, though we may expand to more dialects in the future.
Found via a link on https://weinholt.se/articles/cond-expand-and-ifdef/
I tried to run the trivial program
 (define ! (n) (if (< n 2) 1 (* n (! (1- n)))))
 (display (! 10))
on http://chibi-scheme.appspot.com/, but got an error message about not being able to enlarge memory arrays.