I went through the Microsoft SWE loop twice. Once at L61, once at L63 (senior). Got offers both times, took the second one. Here's what I know now that I wish I'd known before the first loop.
Coding prep: less volume, more depth. Microsoft coding rounds in 2025-2026 are not LeetCode-grind-hard. I've never been asked an LC hard there. Mediums, consistently. The thing is they care about correctness, edge case handling, and communication almost as much as the solution. I'd do maybe 60-80 problems instead of 200, but I'd do each one three ways: solve it, explain it out loud to an imaginary person, then write out edge cases. That's the prep most people skip.
Behavioral prep: understand the culture frame first. Microsoft's interview rubric is built around Satya's "growth mindset" framework. I know that sounds like a buzzword but it has real teeth in their process. Every behavioral question is actually probing for: can you learn, can you take feedback, can you acknowledge failure without being defensive. Before I prepped stories I actually read some of the internal culture docs they've made public and Satya's book. It sounds like overkill but it changed how I framed my answers.
For behavioral, I'd prep 8-10 stories in STAR format but always add an "L" at the end: what you learned. Microsoft interviewers will probe for it.
System design: they care about breadth at L61, depth at L63+. At L61 the bar is more "can you structure a conversation about a complex system." At L63 they want to see you drive the conversation, make explicit tradeoffs, and anticipate follow-up questions before they're asked. I prepped differently for each loop, more breadth the first time, more opinions the second. Know which level you're targeting and calibrate.
The part people don't prep enough: the team fit conversation. Every Microsoft onsite ends with a hiring manager or team conversation that's less structured than the formal rounds. This isn't a throwaway. They're deciding if they want to work with you. Have actual questions about the team, the current technical challenges, the roadmap. Generic "what does success look like" questions read as not having done research.
Timeline: Phone screen to onsite took about 2.5 weeks for me both times. Onsite to debrief result was about a week. Offer stage can be slower. Don't read into timing too much.
One other thing: if your recruiter is responsive and specific, that's a good sign. If they go quiet for a week after onsite, that usually means debrief is still happening, not necessarily bad news.