Initial call with a recruiter, followed by a more technical interview with some of the engineering team. After that I interviewed with the team manger and one of the product managers, and ended with a conversation with HR. The entire process from initial call to receiving the offer was just under a week, honestly very fast and very impressive. I declined the offer because the tech stack is older, specifically .Net Framework (albeit 4.8, so the latest version of the older Framework), and while some work has been done to modernize they're still in the process of doing so and apparently plan to take five to ten years to fully upgrade. I didn't get the impression it would be a very big priority to upgrade to more recent versions of .Net, and was thus concerned about moving back to a much older tech stack. The position would also require me to come on-site on occasion, which makes sense for what they do but wasn't very appealing to me, and the hours could involve early or late calls to coordinate with teams in other countries. Overall everyone was very friendly, and I genuinely commend them for how quickly everything moved. The interview process involved no coding at all, and was basically technical questions.