Ask HN: Which company has the most advanced internal infrastructure?

While reading the google distributed systems papers, I felt how far ahead they would have been of the outside technology stacks back then.

If you have worked in multiple companies, do you think one of them is still vastly ahead in the internal tooling and infrastructure? It could be a big company or a startup. Have you ever felt the technology stack at any of those companies is something the external world is nowhere near?