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Software Engineer 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.
- 9403
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Showing 1921–1950 of 5874 results
- DoorDashMediumSoftware EngineerDebug and refactor a legacy module
This question evaluates debugging, refactoring, naming and exception handling, input validation, code structure, and concurrency-safety design skills within a legacy codebase, requiring both hands-on code changes and higher-level reasoning about immutability, confinement, synchronization, and concurrent data structures.
Coding & AlgorithmsOnsite - DoorDashMediumSoftware EngineerDebug round-robin request router
This interview question evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer for Debug round-robin request router states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignTechnical Screen - DoorDashMediumSoftware EngineerDebug round-robin, DashMap, and simple cache
This question evaluates skills in concurrent programming and stateful selection logic (round-robin load balancing), data structure invariants and debugging (custom hash map hashing vs equality, collision resolution, resizing and iterator correctness), simple in-memory caching strategies with TTL or size-based eviction, and unit test design.
Coding & AlgorithmsTechnical Screen - DoorDashHardSoftware EngineerDebug the Last-Element Random Allocation Case
Implement and test an O(1) randomized pool that avoids and deterministically tests against the classic self-swap regression when removing the tail element.
Software Engineering FundamentalsOnsiteHash TableDesignTesting - DoorDashMediumSoftware EngineerDebug using logs and allocate tasks
This question evaluates a candidate's skill in log-driven debugging, production incident investigation, and cross-functional task allocation, covering competencies such as structured and contextual logging, correlation identifiers, noise reduction, minimal reproducibility, feature-flagged isolation, triage coordination, hypothesis tracking, root-cause confirmation, regression prevention, and blameless postmortems. It is commonly asked to assess operational troubleshooting and teamwork under production uncertainty within the Coding & Algorithms category, testing practical application of debugging techniques alongside conceptual understanding of incident management and process-level coordination.
Coding & AlgorithmsOnsite - DoorDashHardSoftware EngineerDeep-dive a project architecture
An open-ended DoorDash software-engineer system-design screen: pick a real project and deep-dive its architecture end to end. Candidates draw the diagram, state invariants, walk read/write paths, justify storage and trade-offs, capacity-plan, cover reliability/security/observability with SLOs, recount a real incident, and propose a quantified 10x-traffic plan. Includes a full worked example built around a real-time delivery dispatch and live order-tracking service.
System DesignTechnical Screen - DoorDashMediumSoftware EngineerDefend an Ownership Project with Measurable Impact
Tests an engineer's ability to demonstrate end-to-end ownership, justify architectural trade-offs under constraints, and prove business or operational impact using credible metrics.
Behavioral & LeadershipTechnical ScreenOwnershipSystem ArchitectureMetrics & Impact - DoorDashMediumSoftware EngineerDemonstrate leadership and team development
Demonstrate leadership and team development 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 - DoorDashMediumSoftware EngineerDescribe a Project End-to-End
This question evaluates a candidate's ability to demonstrate end-to-end project ownership, technical decision-making, cross-functional communication, and measurement of business impact, and is commonly asked to assess how an individual explains their role, trade-offs, launch outcomes, and lessons learned.
Behavioral & LeadershipTechnical Screen - DoorDashMediumSoftware EngineerDescribe your most impactful recent project
A DoorDash software-engineering onsite behavioral question asking you to walk through your most impactful recent project: the problem, your specific role, measurable impact, a key technical decision and its trade-offs, how you handled scaling and reliability, a risk or failure you hit, and what you'd do differently. Includes a structured STAR-plus-deep-dive framework and a worked real-time-dispatch example.
Behavioral & LeadershipOnsite - DoorDashMediumSoftware EngineerDesign API that aggregates three downstream APIs
This question evaluates a candidate's ability to design an API aggregator, covering skills in service orchestration, fault tolerance, latency and SLO management, error handling, and observability for distributed HTTP/JSON services.
System DesignTechnical Screen - DoorDashMediumSoftware EngineerDesign Food Ratings and Driver Payouts
This question evaluates system design competencies such as API design, data modeling and storage selection for aggregated 5-point ratings, handling user-generated posts and likes, service decomposition, consistency trade-offs, scalability, and designing a monthly batch payout pipeline for driver earnings.
System DesignOnsite - DoorDashMediumSoftware EngineerDesign Food-Item Reviews, Ratings, and Mutable Vote Counts
Design item reviews and votes with purchase eligibility, unique reviews, rating aggregates, reliable counters, pagination, and recoverable caching.
System DesignOnsite - DoorDashHardSoftware EngineerDesign Real-Time Driver Pay Aggregation
This question evaluates competence in designing scalable, fault-tolerant streaming systems and implementing correct time-windowed aggregation logic, testing skills in distributed systems, stream processing, and data correctness; it belongs to the system design domain and streaming/real-time data engineering and spans both conceptual architectural thinking and practical application-level concerns. It is commonly asked to probe reasoning about correctness under at-least-once delivery and messy inputs (out-of-order, duplicate, late, or malformed events), operational resilience, and trade-offs between throughput, latency, and auditability in production-scale pipelines.
System DesignTechnical Screen - DoorDashHardSoftware EngineerDesign a 3-day donation platform
This question evaluates competency in designing scalable, highly available payment-enabled distributed systems, including skills in traffic spike handling, idempotency and reconciliation, real-time totals and leaderboards, latency and throughput planning, and compliance/privacy considerations.
System DesignOnsite - DoorDashMediumSoftware EngineerDesign a Customer Review Page
This question tests the ability to design a scalable review system capable of handling high-write volume, media storage, and efficient retrieval with pagination.
System DesignTechnical ScreenAPIDatabaseScalability - DoorDashMediumSoftware EngineerDesign a Donation Service with Reliable Payment and Payout Tracking
Design donation collection and charity payouts with a PSP, idempotent state transitions, durable ledger records, asynchronous provider events, and reconciliation.
System DesignOnsite - DoorDashMediumSoftware EngineerDesign a Donation System for a Three-Day Fundraising Campaign
Design a donation system for a fundraising campaign that runs for exactly three days, where donors choose a charity, pay through a payment processor and see running totals. It tests payment idempotency and reconciliation, handling a time-boxed traffic burst, avoiding write hotspots on totals, and fraud protection.
System DesignOnsite - DoorDashMediumSoftware EngineerDesign a Durable DAG Workflow for Order Refunds
This problem tests the ability to architect a robust, fault-tolerant workflow engine capable of managing complex state transitions and ensuring transactional integrity in distributed systems.
Software Engineering FundamentalsOnsiteSystem DesignDistributed SystemsWorkflow Engine - DoorDashMediumSoftware EngineerDesign a Food Item Review and Customer Reward System for a Delivery App
A DoorDash system design prompt to build a food item review system for a delivery app that also rewards customers for reviewing. It tests product judgment on open questions, verified-purchase writes, cached rating aggregates, and designing a practical, abuse-resistant reward program with reliable crediting.
System DesignOnsite - DoorDashMediumSoftware EngineerDesign a Food Rating System
This problem tests your ability to design a distributed, read-heavy rating and review system that handles high concurrency and ensures data integrity.
System DesignOnsiteDistributed SystemsCachingAPI Design - DoorDashMediumSoftware EngineerDesign a Food Review Platform
Design a food review platform for discovery, ratings, review text, optional dish-level content, and trusted aggregates. Define entity and review contracts, search and read paths, moderation, abuse resistance, privacy, scaling, and operational recovery.
System DesignOnsite - DoorDashHardSoftware EngineerDesign a Food Review System for a Delivery App, Focused on the Database Schema
System design question for the review feature of a food-delivery platform, where customers rate and review the food from delivered orders and others browse ratings. The focus is database schema design: tables, keys, constraints, indexes, rating aggregates, and how edits, deletes and moderation keep them correct.
System DesignOnsite - DoorDashMediumSoftware EngineerDesign a Food Review and Voting System
Design a scalable review and voting platform for dishes and restaurants, focusing on transactional vote changes, aggregate counter consistency, hot-item read/write scaling, and stable pagination.
System DesignOnsiteDistributed SystemsDatabasesCaching - DoorDashHardSoftware EngineerDesign a Food-Item Review System
Design an item-level review and rating platform for food delivery that handles high-throughput reads, asynchronous sentiment and moderation pipelines, and near real-time score aggregations.
System DesignOnsiteDistributed SystemsData ModelingCaching - DoorDashMediumSoftware EngineerDesign a Menu Item Review and Rating System for a Food-Delivery Platform
A system design question on a menu review feature for a food-delivery platform, where customers rate and review the menu items they ordered. It tests requirement prioritization, detailed review schema and API design, rating aggregation, caching and moderation, and time management that still reaches a deep dive.
System DesignOnsite - DoorDashHardSoftware EngineerDesign a Multi-Service Workflow Engine
Design a resilient, distributed workflow orchestration engine capable of executing multi-step business processes across heterogeneous services with strict guarantees around durability, idempotency, and failure recovery.
System DesignOnsiteDistributed SystemsSaga PatternWorkflow Engine - DoorDashEasySoftware EngineerDesign a Real-Time Monitoring System
This problem tests your ability to design a high-throughput observability pipeline capable of ingesting, storing, and alerting on time-series metrics from a distributed fleet of services.
System DesignOnsiteObservabilityTime-SeriesDistributed Systems - DoorDashMediumSoftware EngineerDesign a Refund Workflow as a Directed Acyclic Graph
Design a resilient, stateful workflow orchestration engine to process complex order refunds as a Directed Acyclic Graph (DAG), ensuring idempotency, crash recovery, and financial consistency.
System DesignOnsitesystem-designdistributed-systemsworkflow-engine - DoorDashMediumSoftware EngineerDesign a Resilient Bootstrap API Aggregator
Design a resilient bootstrap aggregation service that fetches critical initial state for a mobile app on launch. Tests interface design, concurrent I/O, partial failure handling, and operational trade-offs.
Software Engineering FundamentalsTechnical ScreenAPI DesignConcurrencyResilience
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