There were 3 stages on separate days, HR->Engineering Managers->Engineering Director.
HR interview was the usual explanation of the company and role at a high level. It was a good, easy-going chat to see if it suited to continue the process.
The Engineering Manager stage was with two of the team members who explained the role in more detail. Some questions around APIs and Events, and regarding payment processors (Stripe, PayPal, Square, etc.), and a short SQL problem to code while screen sharing.
The final stage was a discussion with one of those same Engineering Mangers and a Director of Engineering. This was similar to the HR interview, in that it was more about the candidate and their experience, and how they thought they would fit in with the team and role requirements.
Overall, everyone I interviewed with were professional and easy to talk with. It felt relaxed and was definitely a positive experience.