Did the Mastercard OA and coding rounds a couple months ago for a senior backend role. Putting this here because the format is a bit different from what you'd expect and I couldn't find fresh data.
Online Assessment (HackerRank): 2 problems, 90 minutes. Both were medium Leetcode difficulty. One was a string manipulation problem (think parsing a transaction log format), the other was a graph problem involving shortest path with constraints. Not a hard, not a grind-50-hards situation. I prepped Neetcode 150 and found that was more than enough coverage.
Time pressure is real though. 90 minutes for 2 mediums sounds generous until you realize the first one has an edge case in the problem description that'll burn 20 minutes if you miss it. Read carefully.
Phone screen coding (live, with recruiter/tech screener): Got a 45-min live coding round after the OA. This was on a shared Google Doc, no IDE, so syntax errors won't save you. The problem was closer to easy-medium. They wanted me to walk through my thinking out loud more than they cared about perfect syntax. My interviewer explicitly said "we care about your approach."
Onsite coding (2 rounds in final loop): Both 60 min, Coderpad. Level felt like medium. One was dynamic programming (not too hard, clear subproblem structure). The other was more of a design-coded problem: implement a simplified version of a rate limiter. Interesting because it bridges into system design territory. You write actual code but need to think about data structures for the rate limiting window.
Overall: The coding bar at Mastercard is solid but not brutal. It's consistent with what I'd call a tier-2 tech company bar. No LC hard in my loop. What they do care about is code quality: variable names, handling null/edge cases, explaining tradeoffs. One interviewer stopped me and asked "what would you change if this had to run in production" and I think that's the actual test.
Did not get the offer but it was close (made it to HC). If I were doing it again I'd spend less time on hard Leetcode and more on writing clean, readable code under pressure.