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Microsoft Senior (L63-L64) Interview Guide
A comprehensive guide to the Microsoft senior interview process.
The Microsoft L63 and L64 senior software engineer interview process typically starts with a recruiter screen, followed by either an online coding assessment or technical phone screen, then moves to the full onsite loop with coding and system design rounds. The entire process usually spans 4 to 5 hours across 4 to 5 separate interviews, though the timeline varies widely based on scheduling and internal approvals. Most teams now default to virtual interviews conducted over Microsoft Teams, with the option to interview onsite if you prefer.
What makes this level distinct is the heavy emphasis on system design and architectural thinking. Senior candidates focus on full system design interviews rather than object oriented design problems. Until L64, there's no dedicated behavioral round - instead, all coding and system design rounds include behavioral evaluation components, and you'll typically be told beforehand what the behavioral focus area will be for each round. Senior candidates are expected to demonstrate not just coding proficiency, but also architectural thinking, reasonable assumptions during ambiguous scenarios, and the ability to scope problems independently rather than waiting for detailed requirements.
Microsoft has a clearly defined interview structure for each level, and candidates are almost always informed about what to expect during their call with the recruiter. If you do get a chance to talk to the hiring manager before the interview (which depends on the organization), ask them what the team will be working on, as this can help focus your preparation on relevant technologies.
The interview consists of 4 to 5 total rounds:
- Initial Recruiter/Hiring Manager Screen
- Online Coding Assessment OR Technical Phone Screen
- Onsite (Usually virtual)
- Coding Interviews (3 rounds, each with behavioral)
- System Design Round (with behavioral)
- As-Appropriate Round (Optional additional interview)
Interview Rounds
Initial Recruiter/Hiring Manager Screen
This opening conversation sets the stage for everything that follows. You'll spend about 30 minutes on a Teams call (occasionally just a phone call) with either your assigned recruiter or the hiring manager directly. The difference matters because each brings a different perspective to the conversation.
When it's a recruiter leading the call, expect a straightforward logistics chat. They'll want to understand your background at a high level, discuss your timeline and any constraints like work authorization, and gauge whether you're genuinely interested in Microsoft versus just fishing for offers. The recruiter will typically ask about how much time you spend in your current role on development, testing, mentoring, and other activities. This call focuses on explaining the interview process, discussing the team, and sometimes sharing prep materials. If the role requires background clearance, they'll cover that too. Recruiters are skilled at reading between the lines, so if you're lukewarm about the company or just going through the motions, they'll pick up on it quickly.
Hiring managers take a different approach. They'll dig a bit deeper into your technical background and previous projects, trying to understand how your experience might translate to their team's challenges. It's still conversational rather than a formal interview, but they're already starting to evaluate whether you'd be a strong addition to their specific group.
You're evaluated on two main aspects during this conversation. First is communication: how clearly you can summarize your experience and what you're looking for in your next role. The second is motivation and fit, which covers both your genuine interest in Microsoft and how well your skills align with what the team needs.
The key to succeeding here is being authentic while showing you've done your homework. Have a crisp two minute summary of your background ready, but more importantly, be prepared to explain why Microsoft appeals to you beyond the obvious factors like compensation or brand recognition. Whether it's excitement about working on Azure infrastructure or wanting to contribute to Office's massive user base, specificity beats generic enthusiasm every time.
Online Coding Assessment
Most senior candidates will encounter Microsoft's online coding test rather than a live technical phone screen. You'll get an email with a link and have flexibility in when you take the assessment, but once you start the 90 minute timer, you're committed to finishing in one sitting.
The format is straightforward but unforgiving. You'll typically see two problems: one that's reasonably approachable and another that's genuinely challenging. The easier problem might involve string manipulation or basic graph traversal, while the harder one could require dynamic programming or complex algorithmic thinking. What makes this particularly tricky is that Microsoft's hidden test cases are comprehensive. A solution that works for the sample inputs but fails on edge cases or large datasets won't cut it.
The online assessment environment feels bare compared to modern IDEs. No autocomplete, no syntax highlighting, no convenient debugging tools. You're essentially coding in a basic text editor, which can be jarring if you're used to robust development environments. The platform does let you run your code against sample test cases, but the feedback is limited. You'll see if your solution passes or fails, but you won't get detailed error messages or insight into which specific test cases are problematic.
Time management is very important. Spend too long perfecting the first problem and you might not even attempt the second one. But rushing through without considering edge cases will likely result in failures on the comprehensive test suite. The sweet spot is getting a working solution for the easier problem quickly, then allocating most of your remaining time to the challenging question.
The evaluation focuses heavily on correctness and efficiency. Microsoft's test cases include edge scenarios like empty inputs, maximum constraints, and unusual data patterns. A brute force approach that times out on large inputs will likely fail, even if the logic is sound. This means you need to think about algorithmic complexity upfront, not just after you've coded a working solution.
"For all the coding rounds, instead of spending too much time explaining in detail, it will save time if the candidate simply starts with a sample input and an expected output. If that aligns well, no further explanation is needed and we can move on to the problem solving part."
— Microsoft Interviewer
Technical Phone Screen (Coding)
Some senior candidates skip the Codility assessment entirely and go straight to a live technical phone screen instead. This tends to happen when you have strong referrals, impressive background credentials, or when the hiring team wants to get a read on your communication style before committing to the full onsite loop.
This is a 60 minute LeetCode style interview with 2 to 3 algorithm and data structure problems. You'll spend about 45 minutes on a Teams call with a Microsoft engineer, starting with a brief chat about your background before diving into the coding problems. These questions are typically easier than what you'd see on Codility, focusing on easy to medium difficulty problems that test your fundamental programming skills.
What makes this different from other phone screens is the collaborative nature. You're not coding in isolation against hidden test cases. Instead, you'll share your screen or use a collaborative editor while talking through your approach. The interviewer acts more like a partner than a silent judge, often providing hints if you get stuck or asking followup questions about your solution.
The questions usually focus on core computer science concepts rather than tricky algorithmic puzzles. You might implement a basic data structure operation, work with strings or arrays, or solve a simple recursive problem. The interviewer cares more about seeing clean, correct code and clear communication than witnessing algorithmic brilliance.
The assessment focuses on three areas:
- Coding Fundamentals: Demonstrates solid understanding of basic programming concepts and ability to implement clean, correct solutions
- Communication: Explains thought process clearly while coding and responds well to interviewer guidance or clarification requests
- Behavioral Potential: Shows collaborative attitude and briefly discusses relevant work experience when prompted
The biggest advantage here is the real time feedback loop. If you misunderstand the problem or head down the wrong path, the interviewer can course correct immediately rather than watching you struggle in silence. Take advantage of this by thinking out loud and asking clarifying questions when the requirements seem ambiguous.
Onsite
Coding Interviews (2 to 3 rounds)
The coding difficulty really steps up from what you experienced in the phone screen or Codility assessment. You'll typically have 2 to 3 separate coding rounds, each lasting 45 to 60 minutes with a Microsoft engineer who will present you with algorithmic and data structure problems. Expect topics like arrays, trees, graphs, and recursion with genuinely challenging variations.
Most problems center around classic computer science concepts but with enough complexity that a straightforward textbook solution won't cut it. The key difference from easier coding rounds is that these problems typically have multiple valid approaches, and part of your evaluation involves choosing the right one. With virtual interviews, interviewers often use questions directly from platforms like LeetCode.
Success depends on four key areas. Problem solving and algorithmic thinking carry the most weight: can you break down a complex problem and apply the right data structures or algorithms? Code correctness is equally critical since the problems are intricate enough that small bugs can derail your entire solution. Efficiency matters too, especially when your first working solution has obvious inefficiencies. Finally, collaboration skills matter because you'll need to communicate your thought process clearly and incorporate feedback from your interviewer.
System Design Interview
This interview carries enormous weight in determining whether you'll land at the 63 to 64 level or get downleveled to something lower. You'll discuss large scale distributed systems for an hour, and the bar is genuinely high. The interviewer will present a broad prompt like "Design a chat application like WhatsApp" or "Build a review system like Yelp" and expect you to architect something that could realistically handle millions of users.
Your interviewer will ask probing questions about your choices, introduce new constraints halfway through, and push you to justify tradeoffs between different approaches. You might start designing a simple messaging system and suddenly they'll ask "How would you handle 10 billion messages per day?" or "What if we need to support video calls too?"
What trips up many candidates is trying to design the perfect system from the start rather than building iteratively. Begin with a basic three tier architecture that handles the core use case, then evolve it based on scale requirements. Your interviewer wants to see how you think through bottlenecks and add complexity only when needed. A candidate who immediately jumps to microservices and sophisticated caching without establishing the foundational data flow often struggles more than someone who starts simple and scales thoughtfully.
"Compared to L61/62, at L63 and L64 candidates are expected to make reasonable assumptions for certain scenarios. Senior engineers and PMs are expected to come up with feature improvement suggestions rather than the lead scoping the problem. If the requirements are ambiguous, is the candidate making reasonable assumptions in order to show progress or are they blocked when things are not clear?"
— Microsoft Interviewer
The evaluation focuses heavily on four areas. Architectural vision means breaking the system into logical services and explaining how they interact. Scalability and reliability covers your knowledge of load balancing, database sharding, replication strategies, and failure handling. Tradeoffs and justification separate strong candidates from average ones since you need to articulate why you chose SQL over NoSQL or eventual consistency over strong consistency. Communication ties it all together because you're essentially thinking out loud for an hour.
The problems themselves tend to focus on systems that Microsoft actually operates at scale. You might design something resembling Teams' messaging infrastructure, Xbox Live's gaming platform, or Azure's storage services. Understanding distributed systems concepts like consistent hashing, message queues, and CDNs becomes crucial since these are the building blocks of any large scale architecture discussion. Scalability is almost always a focus area since most teams deal with solving problems at massive scale.
"Any component or technology used in the design could be picked for deep dive to understand if we really made the right design choice based on what we know about the problem. For example if I have a choice to pick Kafka or SQS or RabbitMQ for a scenario and there's a particular constraint that drives the decision, that has to be called out. Candidates should be prepared for constant interruptions as the interviewer will ask follow up questions whenever something doesn't add up."
— Microsoft Interviewer
"Know everything that you talk about. If you talk about JWT, know how it's implemented to the bit."
— Recent Microsoft Senior candidate
Behavioral Components in Each Round
Until L64, Microsoft doesn't have dedicated behavioral rounds. Instead, each coding and system design round includes a behavioral evaluation component. You'll typically be told beforehand what the behavioral focus area will be for each round, and the interviewer will weave behavioral questions throughout the technical discussion.
The behavioral evaluation focuses on your past projects, leadership experience, conflict resolution, and cultural fit with Microsoft. Interviewers will dig into your work history, asking about specific projects, challenges you faced, mistakes you made, and how you handled difficult situations. The questions systematically probe for evidence of leadership potential, self awareness, and cultural alignment with Microsoft's growth mindset philosophy.
What makes this evaluation important is the heavy emphasis on learning from failure. Microsoft explicitly wants to hear about times when you made mistakes, had poor technical decisions, or faced conflicts with teammates. The trap is trying to spin failures into disguised successes or claiming you've never made significant mistakes. Interviewers can spot these deflections immediately and it raises red flags about your self awareness and honesty.
One question that will definitely be asked somewhere in your interview loop is "Why Microsoft?" The interview panel discusses among themselves who will ask this question, so it's not about if this question will be asked, but when. A good answer should focus on both sides: what you'll achieve by working for Microsoft and what the company gets if they hire you.
Live, up-to-date
Most commonly asked Behavioral questions
Microsoft
Senior
1. Tell me about your approach to make conversations more inclusive
2. Describe your approach to solving new and unfamiliar problems, including any strategies or methodologies you use.
3. Tell me about a change you made that was customer-focused.
4. Tell me about a time you had to change your communication style to solve a problem.
5. Tell me about a time you gave an unfavorable solution to solve a problem.
As-Appropriate Round (Optional)
Some interview loops include an additional meeting with a senior engineer or manager, but this isn't a behavioral interview. Being invited to an "As-Appropriate" round is actually a positive sign that you performed well in earlier rounds. This optional final round typically involves the hiring manager or someone equivalent discussing your areas of interest and talking about typical roles and responsibilities if you join the team.
The format is more like a project-focused discussion driven by the interviewer rather than a formal evaluation. They'll go over what the team is working on, explore how your background aligns with their needs, and give you a clearer picture of what your day-to-day work would look like.
The conversation focuses on practical aspects of the role and team dynamics rather than testing your technical abilities or cultural fit. They might discuss current projects, team structure, career growth opportunities, or how your specific skills would contribute to their goals.
Success in this round comes down to showing genuine interest in the team's work and demonstrating that you've thoughtfully considered how this role fits into your career trajectory.
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