Did Moderna's OA + technical coding round recently. Taking notes while it's fresh because I couldn't find much when I was prepping.
Online assessment (OA): Sent via HackerRank. Two problems, 90 minutes. One was a straightforward string manipulation question, medium difficulty by LC standards, maybe LC medium-easy. Second was a graph traversal problem, nothing exotic. BFS worked fine. No proctoring, time limit was generous enough that I could think through both.
Coding round (live): One 60-minute session, one interviewer. CoderPad. They started with a warm-up: given a list of clinical trial site IDs and their data submission timestamps, find which sites missed their window. Basically a sorting + interval problem. Then a follow-up that added the constraint that some sites share a "parent" site relationship and you need to aggregate by parent.
The interviewer was genuinely nice and gave hints when I was stuck. They said outright they care about how you communicate your thinking more than whether you get to the optimal solution immediately. I solved both but the second took me down a wrong path for about 10 minutes. That was fine.
Observations: Nothing LeetCode hard. Solid mediums. They frame problems in a clinical/bioscience context but you don't need domain knowledge. It's just window dressing on standard algorithmic problems. Python and Java both seem totally fine. I used Python. If you're coming from FAANG, this will feel relaxed. If you're early in your prep, LC medium fluency should get you through.
Target role was senior software engineer. They were clear the OA is a filter, not a heavy signal. The live coding round carries more weight because of the communication component.
Hope this helps someone.