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Microsoft interview notes, page 32 of 60

FAANG / Big Tech

Most of these Microsoft write-ups come from Software Engineers (372), then Product Managers (124) and Machine Learning Engineers (53). The most reported rounds are the technical phone screen (255), the product sense round (111), the system design round (93) and the behavioral / leadership round (49).

597 interview notes · updated Oct 2026

Microsoft·Software Engineer·Technical Phone Screen

May 2026
Microsoft SQL interview, got a classic ranking problem. Short and to the point, nothing too wild.
  • Write a SQL query to rank employees by salary within each department.

“Pretty standard window function territory.”

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Microsoft·Software Engineer·Onsite - System Design / Architecture

May 2026
Microsoft system design round for a software engineering role. The whole session was basically one deep problem about rate limiting, which sounds contained until you realize how many directions they can pull it.
  • Design a Logger class that suppresses duplicate or too-frequent messages within a configurable time window. Define the API, the data structures, thread safety, memory cleanup, and how you'd extend it to support more advanced rate limiting strategies.

“I started with the obvious hashmap approach, message to last-printed timestamp, and they seemed fine with that.”

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Microsoft·Software Engineer·Onsite - System Design / Architecture

May 2026
Microsoft SWE system design round, one big question about sorting a 500 GB file on a single machine with 16 GB of RAM. The whole session was basically one deep dive with follow-ups that kept branching out. Felt like a reasonable interview but the follow-ups on pagination and deduplication caught me a bit flat-footed.
  • You have a single 500 GB CSV file on a machine with only 16 GB of RAM. Design an algorithm and the surrounding system to produce a new CSV sorted by a specified column.
  • How do you choose the chunk size and the merge fan-in? Where does the bottleneck sit, and what do you do if you have more sorted runs than you can merge in a single pass?
  • When would you use a database or a distributed processing engine instead of writing this external sort yourself, and how do you make a multi-hour job restartable if it crashes partway through?
  • If the file grew to 50 TB across a 100-node cluster, how would the design change and how would you handle skew when one key value appears extremely frequently?
  • How would you efficiently serve repeated pagination requests like 'give me rows 1,000,000 to 1,000,050 in sorted order'?
  • How do you make the sort stable, and why might stability matter in this context?
  • If you also need to deduplicate rows that share the same sort key, how do you fold that into the merge without adding a separate pass?

“This is the core question and it took up most of the session.”

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Microsoft·Software Engineer·Technical Phone Screen

May 2026
Microsoft AI Infra interview where the whole session was a live vibe-coding exercise in CUDA. You bring your own editor with an AI assistant set up and they watch how you prompt, critique, and fix the generated kernel code. Pretty different format from the usual whiteboard grind.
  • Using an AI coding assistant in your editor, implement and tune a CUDA kernel (such as tiled matrix multiplication, a fused attention kernel, or a reduction). Walk through your prompting strategy, critique the AI's output, and fix any issues you find.

“This was the whole interview basically.”

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Microsoft·Software Engineer·Technical Phone Screen

May 2026
Short technical screen for a security engineer role at Microsoft. Just one question but it was pretty open-ended and I felt like I could've gone deeper than I did.
  • If you suspected a malicious process was running on a Windows system, where would you look to investigate it?

“I started with the obvious stuff: Task Manager, then moved to Process Explorer for more detail on parent-child relationships and unsigned binaries.”

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Microsoft·Software Engineer·Technical Phone Screen

May 2026
Microsoft SWE interview, got a tree problem that seemed straightforward until I actually had to think about it under pressure.
  • Given a binary search tree and two nodes p and q, find their lowest common ancestor.

“My first instinct was to treat it like a generic tree and do some kind of recursive scan, which would've worked but completely missed the point.”

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Microsoft·Software Engineer·Technical Phone Screen

May 2026
Microsoft SWE interview with a math-heavy algorithm problem that felt more like a calculus class than a coding screen. The core challenge was finding the vertex of a quadratic function you can only call as a black box.
  • You're given a quadratic function as a black box and a range guaranteed to contain its vertex. Find the vertex point.

“My first instinct was binary search and that was wrong.”

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Microsoft·AI Engineer·Onsite - System Design / Architecture

May 2026
System design round at Microsoft for an AI Engineer role. The whole thing centered on building an inventory management system, which sounds boring until you're 20 minutes in and realize you've barely touched half the requirements.
  • Design an item and inventory management system for an e-commerce or warehouse setting. Walk through your functional requirements, data model, and how you'd handle scale.
  • How would you keep a search index like Elasticsearch in sync with your primary database as inventory data changes?
  • How do you ensure stock count consistency when multiple users are trying to reserve the same item at the same time?
  • Would you use a relational database or a document store for the core items and variants data model, and why?

“I started with CRUD on items and variants, which felt like the obvious entry point, but I should've gotten to the stock concurrency piece faster.”

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Microsoft·Machine Learning Engineer·Onsite - System Design / Architecture

May 2026
Interviewed at Microsoft for a machine learning / ranking systems role. The main question was a practical system design problem around deploying and monitoring a ranking model for a social feed product. Not a lot of behavioral stuff, pretty much jumped straight into the technical problem.
  • How would you design the deployment and monitoring pipeline for a social media feed ranking model?

“This is the kind of question that sounds scoped until you actually start answering it and realize it branches everywhere.”

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Microsoft·Machine Learning Engineer·Technical Phone Screen

May 2026
Microsoft ML Engineer interview that went deep on beam search internals. The follow-up question on length normalization was the kind of thing you either know cold or you're fumbling through on the spot.
  • Beam search assigns scores using cumulative log-probabilities, which tend to favor shorter sequences. How would you fix the scoring to make it fair across different sequence lengths, and what are the trade-offs involved?

“I knew the basic fix (divide by length) but fumbled when they pushed on the alpha parameter.”

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