It's currently unpublished because there is an associated cost (Twilio for making the call) and it's not OSS because 1) needs cleaning, 2) was thinking of building a public service out of it.

That said, that's enough of a kick for me to actually clean it up and publish some stuff. I'll email you when I throw pieces of it online (in the next day or two). At the very least, I wasn't able to find a lib that performs all the steps Amazon asks of you to validate the request so I wrote a utility library and hapi auth plugin for that. I'll release those.

Made a quick demonstration video: https://youtu.be/TkVnhp4F1xk