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Pinterest interview notes, page 16 of 24

Large Enterprises

Most of these Pinterest write-ups come from Machine Learning Engineers (91), then Software Engineers (77) and Data Scientists (51). The most reported rounds are the technical phone screen (168), the system design round (37), the product sense round (14) and the behavioral / leadership round (5).

235 interview notes · updated Sep 2026

Pinterest·Software Engineer·Technical Phone Screen

Jun 2026
Pinterest SWE coding round focused on a decimal rounding problem that sounds trivial but ends up requiring a surprising amount of edge case handling. More of a logic exercise than a pure algorithms question.
  • Round the last digit of a non-negative decimal or integer using half-up rounding rules.

“Sounds like a five-minute warmup until you actually start coding it.”

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Pinterest·Machine Learning Engineer·Technical Phone Screen

Jun 2026
Had a technical phone screen for an MLE role at Pinterest that was pretty much a pure ML theory session, about half an hour of back-and-forth on regularization and model generalization. Nothing hands-on, no coding, just concepts.
  • How do you detect overfitting versus underfitting, and how do model capacity and dataset size factor into each?
  • Walk me through L1 vs L2 regularization, including what each actually does to the weights and when you'd choose one over the other.
  • How does dropout work, and what's the intuition behind why it helps generalization?
  • How do L2 regularization and dropout interact when used together in a deep network, and are there any trade-offs to watch for?

“This felt like a warmup but they pushed pretty hard on the nuances.”

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Pinterest·Machine Learning Engineer·Online Assessment (OA)

Jun 2026
Pinterest ML engineer interview with a multiple choice section on ML fundamentals. Pretty calculation-heavy, centered on confusion matrix metrics and knowing your way around TPR/FPR.
  • You are given several data tables and asked to identify which one satisfies a specified combination of true positive rate and false positive rate. Calculate confusion matrix metrics to find the match.

“Took longer than it should have.”

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Pinterest·Data Scientist·Technical Phone Screen

Jun 2026
Pinterest coding round for a Data Scientist role, focused on a systems-flavored design problem about a delay queue. More algorithmic than I expected for a DS position, but apparently this kind of thing shows up there.
  • Design a delay queue that supports scheduling a task with an ID and a future timestamp, and polling for tasks that are ready to run at a given time. Follow-up: if two tasks share the same ID but have different scheduled times, how do you guarantee exactly one of them executes?

“The base implementation wasn't too bad once I landed on a min-heap ordered by run time.”

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Pinterest·Product Manager·Onsite - Product Sense / Strategy

Jun 2026
Interviewed for a PM role at Pinterest and got a product sense question about making e-commerce more inspirational. Pretty on-brand for Pinterest honestly, but that didn't make it any easier to answer well.
  • How could e-commerce platforms improve the shopping experience to feel more inspirational?

“This felt like a Pinterest-flavored question from the start, which I thought would help me but it kind of made me overthink it.”

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Pinterest·Software Engineer·Hiring Manager Screen

Jun 2026
Pinterest hiring manager round, focused entirely on team gaps and how you'd build around them. One question, but it had a lot of surface area.
  • What's the biggest skill or domain gap on your current team, and how would you go about hiring and evaluating someone to fill it?

“This one made me pause longer than I expected.”

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Pinterest·Product Manager·Onsite - Product Sense / Strategy

Jun 2026
Pinterest product interview focused on a monetization decision with real tradeoffs. The core question was about ad placement and whether to break an existing rule for revenue reasons. Pretty intense for what sounds like a single case question.
  • The top-left position in the Pinterest feed has always been reserved for organic content. Given current revenue pressure, how do you decide whether to allow an ad in that slot?

“This one is nastier than it looks.”

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Pinterest·Data Scientist·Technical Phone Screen

Jun 2026
Pinterest DS interview with two SQL problems back to back. Both were heavier than I expected, especially the second one which had multiple moving parts. No behavioral, just pure SQL the whole time.
  • Given impression, user, and pin_info tables, find the pin category with the most impressions today for each country. Return all tied categories if there's a tie.
  • Using the same tables, for each country compute the percentage of active users (at least 1 impression in the last 7 days) who qualify as highly active, where highly active means active on 4 or more distinct days AND used 3 or more distinct surfaces on at least one of those days.

“Knew right away I needed a rank or dense_rank over a count grouped by country and category.”

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

Jun 2026
Pinterest ML system design round, focused entirely on building a recommender system end to end. The depth they wanted on infrastructure surprised me, it wasn't just 'here's a two-tower model' and done.
  • Design a recommender system from scratch. Walk through where you'd store training data, features, and embeddings, how you'd handle offline versus online feature stores, and how you'd serve both the retrieval and ranking models at scale including model registry, low-latency inference, and traffic experimentation.

“This is a lot to cover in one question and I didn't pace myself well.”

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Pinterest·Machine Learning Engineer·Technical Phone Screen

Jun 2026
Pinterest ML Engineer screen that was basically just conceptual theory on Naive Bayes and KNN. Nothing too wild but also not a lot of detail to go on.
  • What are the core assumptions behind Naive Bayes and when do they break down in practice?
  • How does KNN work and what are the tradeoffs involved in choosing the value of K?

“The 'naive' part of the name is the whole ballgame here.”

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