Rigorous and very similar to the likes of Google, Microsoft, etc.
Started with a 3 hour onsite with the director of engineering. Standard behavioral and whiteboard algorithm questions.
After passing this, I was asked to do a take home coding challenge to implement a REST client in any language of my choosing.
After submitting my solution, I was asked to do another 5 hour onsite with 3 additional interviews, mostly technical, with some more behavioral questions.