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Interview Questions
Practice 9403 coding, system design and machine learning questions from 546 companies, sorted by role, topic and interview round. Every question has step-by-step hints, a code runner that supports 8 languages and an AI mentor; members also get the full solution walkthrough.
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Showing 6001–6030 of 9403 results
- NextdoorHardSoftware EngineerDescribe CAP, distributed systems, multithreading experience
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.
System DesignHR Screen - NextdoorMediumMachine Learning EngineerDescribe resume highlights and confirm logistics
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.
Behavioral & LeadershipTechnical Screen - NextdoorMediumSoftware EngineerDesign In-Memory Transactions with Snapshots and Savepoints
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.
Software Engineering FundamentalsTechnical ScreenData StructuresSystem FundamentalsDesign - NextdoorHardData EngineerDesign KPI dashboard tables: retention, weekly rollups, timezone
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.
System DesignTechnical Screen - NextdoorMediumSoftware EngineerDesign a Job Scheduler That Can Scale by 100 Times
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.
System DesignTechnical ScreenDistributed SystemsJob SchedulerScalability - NextdoorMediumSoftware EngineerDesign a Neighborhood Newsfeed System
Design a privacy-aware, hyperlocal social feed that serves real-time updates and emergency alerts based on strict neighborhood boundaries.
System DesignTechnical ScreenFeed ArchitectureGeospatialDistributed Systems - NextdoorMediumSoftware EngineerDesign a Scalable Job Scheduler
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.
System DesignTechnical Screen - NextdoorEasyiOS EngineerFlatten Nested Comments
This problem tests your ability to traverse a nested tree structure (comments) and flatten it into a linear representation while respecting hierarchical depth levels.
Coding & AlgorithmsTechnical ScreenTreesRecursionData Structures - NextdoorMediumSoftware EngineerGroup Photos and Sort Feed Items
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.
Coding & AlgorithmsTechnical ScreenArraysSortingTwo Pointers - NextdoorMediumMachine Learning EngineerImplement ordering with dependency constraints
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.
Coding & AlgorithmsTechnical Screen - NextdoorMediumSoftware EngineerImplement version string comparator with extensions
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.
Coding & AlgorithmsTechnical Screen - NextdoorMediumData ScientistMeasure Local News Launch Success
This problem tests your ability to design an experimentation framework for a localized product launch and identify potential confounding factors and interference effects.
Analytics & ExperimentationTechnical ScreenExperimentationCausal InferenceMetrics - NextdoorMediumMachine Learning EngineerMerge overlapping weekly time intervals
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.
Coding & AlgorithmsTechnical Screen - NextdoorHardSoftware EngineerSimulate Transaction Lock Scheduling
Implement an in-memory lock manager simulating shared and exclusive lock scheduling with strict FIFO queuing to prevent starvation.
Coding & AlgorithmsTechnical ScreenConcurrencyDesignQueue - NextdoorMediumSoftware EngineerWhich culture principle resonates and why
This question evaluates self-awareness, cultural fit, reflective leadership, and communication skills within the Behavioral & Leadership domain for a software engineering role.
Behavioral & LeadershipHR Screen - NextdoorHardData EngineerWrite SQL for app metrics
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.
Coding & AlgorithmsTechnical Screen - NextdoorHardData EngineerWrite SQL for basic user metrics
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.
Coding & AlgorithmsTechnical Screen - NgrokMediumSoftware EngineerGenerate Color Feedback for a Word Guess
Generate green, yellow, or red feedback for each character in a word guess based on positional equality and presence anywhere in the answer. Follow the stated presence semantics, where misplaced duplicate letters remain yellow rather than consuming a limited match count.
Coding & AlgorithmsTechnical Screen - NgrokMediumSoftware EngineerSupport String Membership and Random Sampling
Design an immutable in-memory string collection with exact membership checks and uniform random sampling over stored values. Combine complementary indexing and positional storage, analyze time and memory, and compare the approach with a trie for prefix sharing and future mutations.
Software Engineering FundamentalsTechnical Screen - NielsenMediumSoftware EngineerBehavioral: Walk Through the Project You Are Most Proud Of
A senior behavioral question that asks which project you are most proud of and why, then probes your personal contribution, the hardest decision you made, and the measurable impact. It tests ownership, technical depth, and the ability to explain trade-offs and lessons clearly to an interviewer.
Behavioral & LeadershipOther - NielsenMediumBackend EngineerDesign a Train Ticket Booking System
This problem evaluates your ability to design a robust reservation system that handles concurrent bookings, maintains data integrity, and adheres to clean object-oriented design principles.
Software Engineering FundamentalsTechnical ScreenConcurrencySystem DesignDatabase - NielsenMediumSoftware EngineerDesign a URL Shortening Service: Code Generation, Storage and Fast Redirects
A system design question on building a URL shortening service that turns long links into short codes and redirects visitors quickly at large scale. It tests requirement scoping, capacity estimates, collision-free code generation across servers, storage and caching choices, and how the redirect path behaves under failure.
System DesignOther - NielsenMediumSoftware EngineerPrefix Tree Supporting Insert, Exact Search and Prefix Queries
A coding problem that processes a sequence of insert, exact-match search and prefix-check operations on lowercase words and returns the boolean answers to the queries in order. It tests building a character-level word index and correctly separating whole-word matches from words that are only prefixes of others.
Coding & AlgorithmsOther - NielsenMediumSoftware EngineerSpring Boot Internals and Java 21 Features Behind a Machine Coding Solution
A machine coding follow-up that drills into a Spring Boot service built during the round: startup, auto-configuration, dependency injection and proxies, then the Java 21 features that could improve it, such as sealed types with pattern matching and virtual threads. It tests framework depth and version-aware modern Java knowledge.
Software Engineering FundamentalsOther - NikeMediumSoftware EngineerChoose a Sorting Algorithm from Workload Constraints
Tests your ability to evaluate classical sorting algorithms against concrete workload constraints such as memory access patterns, worst-case guarantees, stability, and streaming limits.
Software Engineering FundamentalsTechnical ScreenSortingAlgorithmsData Structures - NikeMediumSoftware EngineerDesign a PDF Ingestion and Retrieval-Augmented Generation Pipeline
This problem tests the ability to design an end-to-end RAG pipeline capable of handling complex document parsing, chunking strategies for citations, and efficient synchronization of updates.
ML System DesignTechnical ScreenRAGPDF ParsingVector Databases - NikeMediumSoftware EngineerWrite Pseudocode for Embedding Creation and Vector Search
This problem tests the ability to design a robust production pipeline for generating text embeddings and performing efficient, metadata-aware vector retrieval.
Machine LearningTechnical ScreenEmbeddingsVector DBData Pipelines - NioMediumSoftware EngineerFind kth smallest and count stair-climbing ways
This problem tests your ability to implement an efficient selection algorithm for order statistics and a dynamic programming approach to solve a classic combinatorial staircase problem.
Coding & AlgorithmsTechnical ScreenQuickSelectDynamic ProgrammingAlgorithms - NooksMediumSoftware EngineerHow would you throttle a crawler?
This question evaluates competency in scalable distributed system design, including rate limiting, request scheduling, concurrency control, fault tolerance, backoff/retry strategies, deduplication, and observability for networked crawlers.
System DesignOnsite - NooksMediumSoftware EngineerImplement a BFS web crawler
This question evaluates proficiency in breadth-first search and graph traversal concepts applied to web crawling, including handling duplicate links, hostname filtering, and tracking visited URLs.
Coding & AlgorithmsOnsite
Nextdoor
Nielsen