Show HN: CurlSend.it - An API for sending letters from your app or website (curlsend.it)

It seems akin to PixelLetter ⌘ https://www.pixelletter.de/en/ except CurlSend will only send to UK addresses.

If they offered cardboard postcard print, like moo.com but simpler, and a backing legal entity, I'd be coding against it today.

Is there something similar to this in the USA?