I'm a software engineer and applied because I have strong NodeJS/backend/AWS experience. There were two interviews total: first was with the Lead Platform Engineer and second was with Lead Engineer again and COO. There were several questions around AWS and component interconnectivity, including a brief debugging session. I felt like my knowledge was definitely tested so be sure to come prepared (I've been using AWS for years).
I left with a very positive impression of the people and the company as a whole--they seemed very level-headed. I had follow-up questions after the interview and they went out of the way to get back to me promptly.