Pinterest Interview Questions

Pinterest Interview Questions

Practice 145 real Pinterest interview questions for 2026. Covers all top categories — Coding & Algorithms, Data Manipulation (SQL/Python), Analytics & Experimentation, Machine Learning, System Design — across Data Scientist, Software Engineer, Machine Learning Engineer, and Data Analyst roles. Real questions from actual interviews with detailed solutions. This collection leans hard on coding and algorithm problems for SWE candidates while giving equivalent weight to experiment design, SQL/Python analytics, and model evaluation for data roles, making it a focused resource for interview preparation for screens, virtual onsites, and take-home assignments. Expect interviews to evaluate algorithmic thinking, production design, experimental rigor, and clear data storytelling. For Data Scientists you’ll see carousel and billboard lift evaluation, weighted/random-sampling implementations, numpy/pandas and SQL analytics on category and video-time metrics, and survey-balance diagnostics. Software Engineers face prefix-matching, catalog update pipelines, sparse-matrix ops, grid/graph puzzles, and ads event reporting or blob storage design. Machine Learning Engineers get pin-search and recommender design, Naive Bayes/bagging implementation, hyperparameter generation, and sampling-by-score problems. Data Analysts encounter cohort and cancellation/rebooking metric questions. Prepare with timed coding drills, end-to-end A/B case studies, polished Python/SQL practice, and concise STAR stories for behavioral rounds.

145 Questions 1 Company07.23.2026
Showing 20 results
Role
Pinterest logo
Pinterest
Hard
Machine Learning EngineerSenior+ Locked

Design an unsafe content detection system

This question evaluates a candidate's competency in end-to-end machine learning system design for unsafe user-generated content detection, covering mu...

ML System Design
12
0
120 people solved
Jan 12, 2026
Pinterest logo
Pinterest
Hard
Software Engineer

Design a Google Photos–like service

System Design: Google Photos–like Service (Web + Mobile) Context Design a large-scale consumer media service that ingests, stores, indexes, and serves...

System Design
10
0
158 people solved
Sep 6, 2025
Pinterest logo
Pinterest
Medium
Software Engineer

Demonstrate culture fit with examples

Behavioral & Leadership Interview (Software Engineer Onsite) You are preparing for an onsite behavioral and leadership interview for a Software Engine...

Behavioral & Leadership
12
0
106 people solved
Sep 6, 2025
Pinterest logo
Pinterest
Medium
Machine Learning Engineer Locked

Explain bias–variance, overfitting, and vanishing gradients

This question evaluates understanding of core machine learning fundamentals—specifically the bias–variance tradeoff, overfitting detection and mitigat...

Machine Learning
11
0
161 people solved
Jan 22, 2026
Pinterest logo
Pinterest
Medium
Software Engineer

Design highly available blob storage service

Design a large-scale, highly available blob storage service similar to Amazon S3. The service should allow clients to store, retrieve, and delete arbi...

System Design
24
0
184 people solved
Sep 10, 2025
Pinterest logo
Pinterest
Medium
Software Engineer Locked

Design autocomplete and merchant bulk edits

This question evaluates a candidate's system design competency across real-time search/autocomplete and large-scale product update pipelines, covering...

System Design
17
0
199 people solved
Nov 11, 2025
Pinterest logo
Pinterest
Medium
Software Engineer

Build an emoji blaster animation on iOS

iOS "Blaster" App: Press-and-Hold Emoji Projectiles Problem Build a minimal iOS app with a button fixed at the bottom. While the user presses and hold...

Software Engineering Fundamentals
9
0
97 people solved
Sep 6, 2025
Pinterest logo
Pinterest
Hard
Software Engineer

Design Pin recommendation system

Design Pinterest's Home Feed Recommendation System Problem Design an end-to-end recommendation system that powers the personalized home feed on Pinter...

ML System Design
14
0
141 people solved
Jul 28, 2025
Pinterest logo
Pinterest
Medium
Software Engineer Locked

Maximize Boxes Stored Through One Entrance

This question evaluates array manipulation, constraint reasoning, and optimization skills, touching on greedy and combinatorial allocation concepts un...

Coding & Algorithms
2
0
28 people solved
May 19, 2026
Pinterest logo
Pinterest
Hard
Data Scientist

Decide if ad load is optimized

Pinterest Home Feed Ad Load Optimization You are asked to design an analysis and experiment to determine whether the current home-feed ad load (ads pe...

Analytics & Experimentation
25
0
158 people solved
Oct 13, 2025
Pinterest logo
Pinterest
Easy
Machine Learning Engineer

Explain learning-rate fluctuation and vanishing gradients

ML Fundamentals Answer the following conceptual questions: 1. Learning rate vs. training stability: Why can training metrics (loss/accuracy) fluctuate...

Machine Learning
9
0
105 people solved
Dec 15, 2025
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Pinterest
Hard
Data Scientist

Demonstrate leadership with concrete STAR examples

Behavioral & Leadership (Onsite) — STAR Examples With Metrics Provide succinct STAR-format examples (Situation, Task, Action, Result), with specific m...

Behavioral & Leadership
12
0
103 people solved
Oct 13, 2025
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Pinterest
Hard
Data Scientist

Recover causal effect without a control group

Post-hoc Causal Estimation After a Failed A/B Rollout Context An intern accidentally shipped a feature to 100% of eligible users for 5 consecutive day...

Analytics & Experimentation
15
0
103 people solved
Oct 13, 2025
Pinterest logo
Pinterest
Medium
Data Scientist

Estimate Highway Billboard Impressions Using Traffic Data

Estimating Highway Billboard Reach and Impressions An out-of-home advertising team wants to estimate reach and impressions for a single highway billbo...

Statistics & Math
31
0
142 people solved
Jul 12, 2025
Pinterest logo
Pinterest
Hard
Machine Learning Engineer

Design an ads system to improve CTR

Design an ML system to increase the click-through rate (CTR) of ads shown in the personalized feed of an online social media platform. You run the ran...

ML System Design
17
0
148 people solved
Dec 13, 2025
Pinterest logo
Pinterest
Medium
Data Scientist

Design and Evaluate a Home Carousel

Pinterest is considering adding a horizontally scrollable carousel at the top of the Home feed, similar to Instagram Stories. The carousel may surface...

Analytics & Experimentation
7
0
119 people solved
Jan 14, 2026
Pinterest logo
Pinterest
Hard
Data Scientist

Design rigorous A/B test and causal analysis

Experiment Design and Causal Inference: Multi-part Problem Context: You are designing a high-traffic web A/B test on a binary conversion metric. Answe...

Statistics & Math
16
0
143 people solved
Oct 13, 2025
Pinterest logo
Pinterest
Hard
Data Scientist

Analyze survey with gender imbalance

Analyze survey with gender imbalance Scenario You ran a user survey to measure satisfaction with a new product feature. Each respondent reports: - gen...

Statistics & Math
14
0
116 people solved
Aug 2, 2025
Pinterest logo
Pinterest
Medium
Machine Learning Engineer Locked

First Word Matching Each Prefix Query

This question evaluates a candidate's grasp of string data structures and efficient prefix-matching techniques, core competencies in coding and algori...

Coding & Algorithms
1
0
11 people solved
Jun 3, 2026
Pinterest logo
Pinterest
Medium
Software Engineer

Mark and Compact a Heap-Indexed Subtree

Mark and Compact a Heap-Indexed Subtree An interview report describes an array-encoded tree, marking a target and its descendants with -1, then moving...

Coding & Algorithms
1
0
19 people solved
Jul 2, 2026

Frequently Asked Questions

How difficult are Pinterest interview questions for this 145-question set?
Pinterest interview difficulty varies by role and seniority. Across the 145 real questions in this set, expect medium-to-hard difficulty for software engineers with emphasis on clean algorithmic solutions and system tradeoffs, and moderate-to-hard for data scientists where product-focused experimentation, SQL, and causal reasoning are evaluated. Machine learning engineer rounds skew toward applied ML fundamentals and recommender/search design, while data analyst items are relatively straightforward metric calculations. Overall, interviews test both implementation fluency and product judgment — solving a problem correctly is necessary, but explaining assumptions, metrics, and tradeoffs is equally important.
What is the typical Pinterest interview process and where do these roles appear in the loop?
Pinterest interviews usually begin with a recruiter screen, followed by one or two technical screens tailored to the role, then a loop of 3–5 onsite or virtual interviews covering coding, system or ML design, and behavioral/manager rounds. Software engineer candidates see coding and system-design-focused rounds; data scientists face coding plus product-case and experimentation rounds; machine learning engineers combine coding with model design and recommender/search architecture; data analysts are asked metric and SQL problems. Expect the role to surface early in the loop during the technical screens so prepare role-specific artifacts and examples in advance.
How should I schedule preparation across the 145 real Pinterest interview questions — what timeline works best?
For 145 questions allocate a structured 6–8 week plan: weeks 1–2 reinforce fundamentals — arrays, strings, hashes, SQL joins/aggregates, and core ML statistics; weeks 3–5 work through the dataset: alternate role-specific blocks (coding for engineers, experiment and SQL cases for data scientists, model and recommender design for MLEs) and time-box solving full questions under interview conditions; final 1–2 weeks run timed mock interviews, system design walkthroughs, and behavioral STAR rehearsals. Review mistakes, write clean solutions, and practice explaining metrics and tradeoffs out loud before interviewing.
What are the key technical subtopics to prioritize from these Pinterest questions?
Prioritize the themes that appear repeatedly by role. For data scientists focus on experiment design and lift evaluation (carousel and billboard cases), weighted or random sampling implementations, SQL aggregation for top categories and engagement metrics, and handling survey biases. Software engineers should emphasize prefix/autocomplete patterns, pipeline and storage design, sparse-matrix algorithms, graph and grid search problems, and reliability for blob/event systems. Machine learning engineers need search/recommender architecture, model fundamentals (bagging, Naive Bayes), hyperparameter grid generation, and overfitting diagnostics. Data analyst items concentrate on retention and cancellation percent calculations.
What standout tips and common pitfalls should I watch for when prepping these Pinterest interview questions?
Lead with product context and metrics: state the business goal, choose evaluation metrics, and justify tradeoffs. Communicate assumptions, handle edge cases, and write tests or sample outputs for coding/SQL answers. For experiments, state randomization strategy, power implications, and bias controls. For ML, discuss features, regularization, and validation to avoid overfitting. Pitfalls include skipping requirement clarifications, ignoring NULLs or real data skew, overengineering a solution, and failing to link technical choices back to user or business impact. Practice concise storytelling for behavioral rounds and timed mock interviews for fluency.

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