Nextdoor interview questions

Showing 1–21 of 21 results

• Answer HR motivation and project experience questionsMedium

  This interview question evaluates behavioral evidence, ownership, communication, trade-offs, and measurable outcomes in a realistic interview setting. A strong answer for Answer HR motivation and project experience questions states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

  NextdoorMachine Learning EngineerBehavioral & LeadershipTechnical Screen
• Build Ranked Feed With Photo BatchingMedium

  This question evaluates algorithmic reasoning and data manipulation skills, including stable sorting, grouping/batching, and merging of ranked items while preserving ordering invariants.

  NextdoorMachine Learning EngineerCoding & AlgorithmsTechnical Screen
• Build a model using only pandas/numpyMedium

  This question evaluates proficiency in applied machine learning competencies including data preprocessing, categorical encoding, feature scaling, implementing baseline models and optimization using numpy/pandas, and selecting appropriate evaluation metrics.

  NextdoorMachine Learning EngineerMachine LearningTechnical Screen
• Build an end-to-end ML classification pipelineMedium

  This question evaluates a candidate's competency in building end-to-end tabular classification pipelines, including data loading and splitting, missing-value handling, categorical encoding, feature scaling, model training and comparison, hyperparameter tuning, metric-based evaluation, model persistence, and batch inference.

  NextdoorMachine Learning EngineerML System DesignTechnical Screen
• Describe CAP, distributed systems, multithreading experienceHard

  This question evaluates practical and theoretical competence in the CAP theorem, distributed system architecture, and multithreaded concurrency, covering consistency models, partition tolerance, fault tolerance, scaling strategies, synchronization primitives, and debugging/performance techniques.

  NextdoorSoftware EngineerSystem DesignHR Screen
• Describe resume highlights and confirm logisticsMedium

  Describe resume highlights and confirm logistics evaluates behavioral evidence, ownership, communication, trade-offs, and measurable outcomes in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.

  NextdoorMachine Learning EngineerBehavioral & LeadershipTechnical Screen
• Design In-Memory Transactions with Snapshots and SavepointsMedium

  Tests your ability to design an in-memory key-value store supporting nested transactions, named savepoints, and reliable rollback semantics using undo logs or snapshotting.

  NextdoorSoftware EngineerSoftware Engineering FundamentalsTechnical Screen
• Design KPI dashboard tables: retention, weekly rollups, timezoneHard

  This Nextdoor data engineer system design screen asks you to design the analytical data model and incremental ETL behind a fast, large-scale KPI dashboard for a photo-sharing app. It covers derived aggregate table design (grain, keys, partitioning), DAU/new-user/new-photo and follower-distribution metrics, 7-day deltas, then extends to week-1 cohort retention, weekly rollups, and switching the reporting timezone. The focus is correctness, performance at scale, and maintainability with timezone handled as a reporting parameter.

  NextdoorData EngineerSystem DesignTechnical Screen
• Design a Job Scheduler That Can Scale by 100 TimesMedium

  Design a distributed, asynchronous job scheduler that starts at modest traffic but can seamlessly scale up 100x. Evaluates API design, data storage trade-offs, worker coordination, task deduplication, and failure handling across scale boundaries.

  NextdoorSoftware EngineerSystem DesignTechnical Screen
• Design a Neighborhood Newsfeed SystemMedium

  Design a privacy-aware, hyperlocal social feed that serves real-time updates and emergency alerts based on strict neighborhood boundaries.

  NextdoorSoftware EngineerSystem DesignTechnical Screen
• Design a Scalable Job SchedulerMedium

  This question evaluates system design skills focused on job scheduling, distributed systems concerns (state modeling, retries, idempotency), API and data-model design, fault tolerance, observability, and scalability within the System Design domain.

  NextdoorSoftware EngineerSystem DesignTechnical Screen
• Flatten Nested CommentsEasy

  This problem tests your ability to traverse a nested tree structure (comments) and flatten it into a linear representation while respecting hierarchical depth levels.

  NextdooriOS EngineerCoding & AlgorithmsTechnical Screen
• Group Photos and Sort Feed ItemsMedium

  Implement a feed transformation that collapses consecutive photo posts by the same user into album items and then stably sorts the resulting feed by timestamp.

  NextdoorSoftware EngineerCoding & AlgorithmsTechnical Screen
• Implement ordering with dependency constraintsMedium

  This question evaluates understanding of dependency resolution and ordering within graph-based problems, including cycle detection, lexicographic tie-breaking, and extensions requiring certain items to appear as contiguous groups.

  NextdoorMachine Learning EngineerCoding & AlgorithmsTechnical Screen
• Implement version string comparator with extensionsMedium

  This question evaluates string parsing and comparison algorithms, handling of numeric versus lexical ordering and versioning semantics (including pre-release identifiers and ignored build metadata), within the Coding & Algorithms domain.

  NextdoorSoftware EngineerCoding & AlgorithmsTechnical Screen
• Measure Local News Launch SuccessMedium

  This problem tests your ability to design an experimentation framework for a localized product launch and identify potential confounding factors and interference effects.

  NextdoorData ScientistAnalytics & ExperimentationTechnical Screen
• Merge overlapping weekly time intervalsMedium

  This question evaluates the ability to parse weekday and 24-hour time strings, reason about interval overlap, and apply efficient merging and sorting techniques for time-based intervals.

  NextdoorMachine Learning EngineerCoding & AlgorithmsTechnical Screen
• Simulate Transaction Lock SchedulingHard

  Implement an in-memory lock manager simulating shared and exclusive lock scheduling with strict FIFO queuing to prevent starvation.

  NextdoorSoftware EngineerCoding & AlgorithmsTechnical Screen
• Which culture principle resonates and whyMedium

  This question evaluates self-awareness, cultural fit, reflective leadership, and communication skills within the Behavioral & Leadership domain for a software engineering role.

  NextdoorSoftware EngineerBehavioral & LeadershipHR Screen
• Write SQL for app metricsHard

  This question evaluates proficiency in SQL-based data engineering, focusing on time-zone-aware timestamp handling, aggregation of event and relationship data, cohort retention analysis, and computation of product metrics like DAU, new users, photo activity, and follower distributions.

  NextdoorData EngineerCoding & AlgorithmsTechnical Screen
• Write SQL for basic user metricsHard

  This question evaluates proficiency in SQL for relational databases, specifically testing aggregation, joins, date/time grouping, and handling tied results when computing user metrics such as total users, peak signup month, and top-followed users.

  NextdoorData EngineerCoding & AlgorithmsTechnical Screen