from the blog linked via Wayback Machine. "From Day 1, we had this notion at the forefront.
The other notion that we have intuited is that you can’t build a cloud on another cloud. We have devoted years of practice running our own metal (and playing well with other clouds) to make sure that Railway’s business, which invariably becomes your customer’s business, is as rock solid as possible."
That’s strange, when I interviewed with the founder a few years ago he told me they were on AWS wanting to move to firecracker.