TLDR: We built out an API for sending handwritten letters at https://www.handwrite.io/handwritten-notes-api
Quick backstory: I was helping a small moving company build out some marketing automation as a side gig.
We were ingesting housing data and as soon as a house went up for sale, we'd use lob.com to send a direct mail postcard letting the home owner know we'd love their business.
But the postcards didn't convert well, and were super cliche so I went searching for something that might feel a little more personal.
That's when I met my cofounder, Dan, here on Hacker News! (Here's the comment actually: https://news.ycombinator.com/item?id=19780024)
We joined forces and worked the past few months to build out a new web application, several new handwriting robots, and of course an API!
We'd love any feedback you have, or if you want to integrate it into your business, hit me up at firstname.lastname@example.org and I'll get you on our special HN pricing (no monthly recurring, only pay per use).