Backend Engineer Interview Questions

Showing 1–30 of 91 results

• AirbnbHard·Backend Engineer
  Design a Rental Marketplace Backend

  This problem tests your ability to design a distributed, high-scale rental marketplace platform, focusing on concurrency control for bookings, efficient geo-spatial searching, and data consistency.

  System DesignOnsiteDistributed SystemsConcurrencyGeo-spatial
• AirwallexMedium·Backend Engineer
  AI-Assisted Build: Tic-Tac-Toe Logic Grown Into a Frontend and Backend App

  An AI-assisted coding exercise: build a two-player Tic-Tac-Toe game, then grow it into an application with a frontend and a backend while using AI tools. Tests correct game rules, server-side validation, API design, and the ability to understand, debug and verify AI-generated code.

  Software Engineering FundamentalsOther
• AirwallexMedium·Backend Engineer
  Bar-Raiser Project Deep Dive: Defending Decisions, Trade-offs, Impact and Lessons

  A bar-raiser round that deep-dives into one of your past projects, probing each decision through layers of why, the trade-offs accepted, the measured impact and the lessons learned. Tests ownership, judgment, honest reflection and consistency under repeated follow-up questions.

  Behavioral & LeadershipOnsite
• AirwallexMedium·Backend Engineer
  Design a Hotel Booking Platform Down to the SQL Tables and Booking Transaction

  Design a hotel booking platform where travelers search by destination and dates and book rooms, down to the SQL tables and the booking transaction. Tests schema design with real constraints, preventing double booking under concurrency, payment holds and expiry, and a search path that scales separately.

  System DesignOther
• AirwallexMedium·Backend Engineer
  Maximum Triangle Path Sum, Overall and Through a Required Cell

  Given an integer triangle where each step moves to one of the two adjacent cells in the next row, return the maximum top-to-bottom path sum and the maximum sum among paths forced through a given cell. Tests dynamic programming on a triangle and adapting it to a constrained follow-up.

  Coding & AlgorithmsOther
• Applied IntuitionHard·Backend Engineer
  Resolve Dependent Addition Equations

  Implement an equation evaluator that computes the integer values of variables defined in terms of literals and other variables while detecting cycles and undefined references.

  Coding & AlgorithmsTechnical ScreenGraphTopological SortDFS
• ArmMedium·Backend Engineer
  Describe leadership, AI perspective, and challenges

  This question evaluates leadership, communication, problem-solving, resilience, and the ability to articulate ethical and strategic perspectives on AI as they relate to engineering work.

  Behavioral & LeadershipOnsite
• ArmMedium·Backend Engineer
  Explain timing and testability concepts

  This question evaluates a candidate's understanding of digital timing and testability concepts—specifically setup and hold timing, clock skew impacts, mitigation of setup/hold violations, and test methodologies such as scan, DFT and MBIST—within backend digital implementation contexts.

  Software Engineering FundamentalsOnsite
• BByteDanceHard·Backend Engineer
  Backend Fundamentals Deep Dive: MySQL Internals, Redis, and the HTTP/HTTPS Request Lifecycle

  This problem tests your depth in database durability mechanisms, caching strategies for consistency, and the network-level steps involved in secure HTTP request handling.

  Software Engineering FundamentalsTechnical ScreenMySQLRedisSystem Design
• BByteDanceHard·Backend Engineer
  Explain Backend Fundamentals and AI Tooling

  This question tests foundational knowledge across systems engineering, database design, version control, and modern AI integration strategies.

  Software Engineering FundamentalsHR ScreenSystems DesignDatabasesGit
• BByteDanceHard·Backend Engineer
  SQL: Students Above Average and Passing Every Subject

  This problem tests advanced SQL skills, including the use of window functions, conditional aggregation, and multi-level filtering to identify subsets of data that satisfy both global and per-category criteria.

  Data Manipulation (SQL/Python)Technical ScreenSQLAggregationWindow-Functions
• BByteDanceHard·Backend Engineer
  Solve Bracket Matching and Tree Width

  This problem tests string manipulation and tree traversal techniques by requiring the validation of complex bracket sequences and the calculation of the maximum horizontal distance between nodes at the same level of a binary tree.

  Coding & AlgorithmsHR ScreenStacksBFSTrees
• ChimeMedium·Backend Engineer
  Design browser history across tabs

  This question tests the ability to design an efficient data structure for navigating browser history, requiring careful management of back/forward states across multiple independent tabs.

  Software Engineering FundamentalsTechnical ScreenData StructuresStacksHash Maps
• ChimeMedium·Backend Engineer
  Solve classic backend coding problems

  This problem tests your ability to handle string manipulation, recursion with backtracking, and mapping logic by generating all valid word combinations from a numeric keypad sequence.

  Coding & AlgorithmsTechnical ScreenBacktrackingRecursionStrings
• CoinbaseMedium·Backend Engineer
  Design a Real-Time Asset Price Service

  Design a high-throughput, low-latency price ingestion and distribution service that normalizes multi-exchange market data, reconciles conflicting ticks, and delivers live prices to internal services and retail clients.

  System DesignOnsiteDistributed SystemsWebSocketsReal-Time Data
• CoinbaseMedium·Backend Engineer
  Evolve Cursor Pagination Without Breaking Clients

  This problem tests the ability to design stable, deterministic cursor-based pagination systems that handle non-unique sort keys and schema evolution without breaking backward compatibility.

  Software Engineering FundamentalsOnsiteAPI DesignPaginationSQL
• CoinbaseMedium·Backend Engineer
  Implement a Stateful Trading Order Manager

  This problem tests your ability to design a stateful system using hash-based sharding, efficient indexing, and robust state machine transitions for high-frequency financial orders.

  Coding & AlgorithmsOnsiteHash TablesSystem DesignState Machines
• CCourseraHard·Backend Engineer
  Implement Popular and Ranked Voting

  This question evaluates algorithmic implementation skills and understanding of voting systems, including aggregation of first-place preferences and the conceptual mechanics of elimination-based ranked-choice counting.

  Coding & AlgorithmsTechnical Screen
• CrowdstrikeMedium·Backend Engineer
  Implement a Risk-Score Priority DetectionStore With Put and GetNext in C++

  Implement a C++ DetectionStore whose Put stores security detections with an id, an unsigned risk score and a payload, and whose GetNext removes and returns the next detection by risk score as a unique_ptr. Tests priority-structure choice, ownership semantics, tie and duplicate-id policies, and thread safety.

  Software Engineering FundamentalsTechnical Screen
• CursorMedium·Backend Engineer
  Design Scalable Notification Rate Limiter

  This question evaluates expertise in designing distributed rate-limiting systems with hierarchical quotas, focusing on concurrency control, exact rolling-window counting, and correctness under concurrent stateless servers; it belongs to the System Design domain and tests practical application of distributed systems, storage, and API design as well as conceptual understanding of atomicity and consistency. It is commonly asked to assess reasoning about atomic decision-making across multiple scopes, scalability and partitioning strategies, handling reconfiguration and operational concerns, and the trade-offs between correctness and system performance (English).

  System DesignTechnical Screen
• DatabricksMedium·Backend Engineer
  Design a Distributed File System

  This question tests the ability to design a scalable, fault-tolerant distributed file system by addressing challenges in metadata management, data chunking, and cluster availability.

  System DesignTechnical ScreenDistributed SystemsStorageScalability
• DatabricksMedium·Backend Engineer
  Design a Distributed File System, Scoping the Requirements Yourself

  Design a distributed file system from a one-line prompt, driving the scoping of workload, semantics, scale and durability yourself. Tests separating metadata from data, block replication and placement, read and write paths, failure recovery, and scaling the namespace for a staff-level backend role.

  System DesignOnsite
• DatabricksMedium·Backend Engineer
  Find First Anagram Occurrence

  This question evaluates proficiency in string processing, character-frequency analysis, and efficient substring search techniques, measuring competency in algorithmic reasoning and implementation for pattern matching.

  Coding & AlgorithmsTechnical Screen
• HarveyMedium·Backend Engineer
  Design a secure document vault

  This question evaluates a candidate's competencies in secure backend system design, covering authentication and authorization, metadata and object storage architectures, integrity verification for chunked uploads, scalability, and operational reliability.

  System DesignOnsite
• HarveyMedium·Backend Engineer
  Explain project decisions and trade-offs

  This question evaluates proficiency in technical decision-making, trade-off analysis, and system design ownership for backend projects, including architecture rationale, technology selection, and the candidate's specific role and measurable impact.

  Software Engineering FundamentalsOnsite
• HarveyMedium·Backend Engineer
  Implement tag matcher and filesystem

  This combined prompt evaluates string-processing and parsing skills for tag matching and design/implementation skills for an in-memory file system, measuring competencies in exact whole-word matching, case normalization, punctuation and duplicate handling, path parsing, hierarchical data structures, and file API behaviors.

  Coding & AlgorithmsOnsite
• HarveyMedium·Backend Engineer
  Resolve conflict across teams

  This question evaluates conflict resolution, stakeholder alignment, cross-team communication, and leadership competencies in the context of engineering coordination, classified under Behavioral & Leadership for a backend engineer role.

  Behavioral & LeadershipOnsite
• InstacartMedium·Backend Engineer
  Debug Metrics Computed Before Filtering

  Debug a metrics endpoint whose summary is calculated before user filters are applied even though its rows are filtered correctly. Trace the data lineage, aggregate over the full matched population before pagination, preserve security scoping, and add unit and endpoint regression tests.

  Software Engineering FundamentalsOnline Assessment
• InstacartMedium·Backend Engineer
  Design Idempotent Due-Date and Hold Notifications

  Design idempotent library notifications for upcoming and current due dates plus FIFO hold availability. Use stable business-event identities, transactional scheduling, atomic recipient claims, state rechecks, retries, reconciliation, and clear frontend distinctions among holds, offers, and checkouts.

  System DesignOnline Assessment
• InstacartMedium·Backend Engineer
  Fix the Broken Search Filter in a Book Catalog API

  This problem tests your ability to sanitize inputs and implement robust filtering logic on a collection of structured objects using multiple criteria.

  Coding & AlgorithmsOnline AssessmentFilteringStringsBackend