Backend Engineer Interview Questions

Showing 1–25 of 25 results

• 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
• 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
  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
• 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
• 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
  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
• NielsenMedium·Backend Engineer
  Design 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
• OpenAIMedium·Backend Engineer
  Convert IPv4 Ranges to CIDR Blocks

  This question evaluates understanding of IPv4 addressing, binary/bitwise manipulation, and the ability to summarize consecutive address ranges into minimal CIDR blocks, and belongs to the Coding & Algorithms domain for backend engineering roles.

  Coding & AlgorithmsTechnical Screen
• OOpendoorMedium·Backend Engineer
  Design Map-Based Home Search

  This problem tests the ability to design a geo-spatial search service capable of handling high-frequency map interactions, filtering, and data consistency at scale.

  System DesignTechnical ScreenGeo-spatialCachingScaling
• OOpendoorHard·Backend Engineer
  Execute a TTL Key-Value Store with Transactions

  This problem tests the implementation of an in-memory key-value store supporting TTL expiration, atomic transactions with rollback capabilities, and logical time-based validation.

  Coding & AlgorithmsTechnical ScreenHashMapsTransactionsTTL
• OOtherMedium·Backend Engineer
  Compare Strings With Deletions

  This question evaluates string processing and algorithmic optimization skills, specifically handling simulated deletions (backspace behavior) and performing comparisons under a strict auxiliary space constraint.

  Coding & AlgorithmsTechnical Screen
• RedditMedium·Backend Engineer
  Design Tennis Scoring with Pluggable Rules

  Design a testable tennis game scoring component with point recording, readable scores, terminal-state handling, and stable player identity. Keep standard Deuce and Advantage rules separate from pluggable alternatives such as no-ad scoring, and discuss audit history and serialization.

  Software Engineering FundamentalsTechnical Screen
• RRilletMedium·Backend Engineer
  Distribute Annual Revenue Across Twelve Months

  This problem tests logic, integer arithmetic, and edge-case handling by requiring the distribution of a total sum into equal parts while managing remainders without using floating-point numbers.

  Coding & AlgorithmsTechnical ScreenAlgorithmsInteger ArithmeticData Manipulation
• RobinhoodMedium·Backend Engineer
  Count and Rank Words in a Paragraph

  This problem tests string manipulation, hash map usage for frequency counting, and custom sorting logic for deterministic ordering.

  Coding & AlgorithmsTechnical ScreenStringsHash MapSorting
• RobinhoodMedium·Backend Engineer
  Critique a Recent Engineering Project and Explain What You Would Redo

  Prepare a candid deep dive on a recent engineering project, including personal ownership, a consequential technical decision, and observed outcomes. Identify a real weakness, trace its cause, and explain what you would redesign today.

  Behavioral & LeadershipTechnical Screen
• RobinhoodMedium·Backend Engineer
  Deep-Dive a Distributed Service Project

  This question assesses a candidate's ability to articulate the architecture, constraints, and operational challenges of a distributed system they previously owned, while demonstrating clarity in personal impact and technical decision-making.

  Behavioral & LeadershipTechnical ScreenSystem DesignDistributed SystemsCommunication
• RobinhoodMedium·Backend Engineer
  Scale Word-Frequency Processing Beyond One Machine

  This question tests the ability to design a distributed data processing pipeline that handles large-scale text files by balancing memory constraints, horizontal scalability, and data integrity.

  System DesignTechnical ScreenDistributed SystemsMapReduceScalability
• SpotifyMedium·Backend Engineer
  Longest Contiguous Stretch of Distinct Characters in a String

  A Spotify backend technical-screen coding problem: given a string, find the length of the longest contiguous substring in which no character repeats. It tests careful string scanning, linear-time reasoning, and edge cases such as case sensitivity, ties and empty input.

  Coding & AlgorithmsTechnical Screen
• UberMedium·Backend Engineer
  Replace Dashes With Nearest Letters

  This problem tests your ability to perform a multi-source shortest path search on a grid to determine the influence of characters on empty spaces, using Manhattan distance and lexicographical tie-breaking.

  Coding & AlgorithmsTechnical ScreenBFSGridGraph
• ZipHQMedium·Backend Engineer
  Find Bugs in an LRU Cache

  Identify behavioral bugs in a Java-based LRU Cache implementation using LinkedHashMap, write minimal failing tests, and provide the corrected code.

  Software Engineering FundamentalsTechnical Screenjavadata-structuresdebugging
• ZooxMedium·Backend Engineer
  Design Real-Time Vehicle Location Tracking

  Design a high-throughput, low-latency telemetry ingestion and distribution system that streams autonomous vehicle coordinates to client dashboards and rider apps.

  System DesignTechnical ScreenReal-TimeGeospatialWebSockets