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Backend 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
- Questions
- 546
- Companies
- 11
- Topics
- 8
- Languages
Showing 1–30 of 55 results
- AirbnbHardBackend EngineerDesign 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 - AirwallexMediumBackend EngineerBar-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 - ArmMediumBackend EngineerDescribe 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 - ArmMediumBackend EngineerExplain 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 - CoinbaseMediumBackend EngineerDesign 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 - CoinbaseMediumBackend EngineerEvolve 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 - CoinbaseMediumBackend EngineerImplement 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 - DatabricksMediumBackend EngineerDesign 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 - HarveyMediumBackend EngineerDesign 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 - HarveyMediumBackend EngineerExplain 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 - HarveyMediumBackend EngineerImplement 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 - HarveyMediumBackend EngineerResolve 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 - LatitudeaiMediumBackend EngineerDesign a Thread-Safe Bounded Blocking Queue
Tests your ability to design a concurrent, thread-safe bounded blocking queue using synchronization primitives, handle edge cases like spurious wakeups and timeouts, and cleanly coordinate shutdown across multiple threads.
Software Engineering FundamentalsOnsiteConcurrencyMultithreadingQueue - LegoraMediumBackend EngineerDesign a Cloud-Agnostic Upload Adapter
Design a provider-neutral object storage upload client that unifies cloud SDK behaviors while supporting streaming, multipart uploads, error normalization, and provider-specific escape hatches.
Software Engineering FundamentalsOnsiteapi-designcloud-storageobject-oriented-design - MetaMediumBackend EngineerSolve coding and AI-assisted tasks
This problem tests your ability to manipulate tree structures with parent pointers and verify path validity under specific movement constraints.
Coding & AlgorithmsOnsiteTreesData StructuresAlgorithms - MintlifyMediumBackend EngineerDesign a CRUD API for a document service
Design the create, read, update and delete API for a document service, covering the resource model, endpoints, request shapes and status codes. It tests REST fundamentals plus production concerns such as concurrent edits, idempotent retries, pagination, authorization, deletion semantics and API versioning.
Software Engineering FundamentalsOnsite - MintlifyMediumBackend EngineerHiring-manager screen: past work, full-stack flexibility, and why join a startup
A hiring-manager screen for a senior backend role asks you to walk through your previous work, describe your full-stack experience and whether you would take on frontend work, and explain why you want to join a startup and this company. It tests concise storytelling, flexibility and genuine motivation.
Behavioral & LeadershipOnsite - MintlifyMediumBackend EngineerShould you add an index for a slow query on a large table's unindexed columns?
A query on a large database table is slow and the columns it filters on have no index: should you add one? It tests reading query plans, weighing selectivity and query frequency against write cost, designing composite or partial indexes, and building an index safely on a busy production table.
Software Engineering FundamentalsOnsite - New RelicMediumBackend EngineerCompress a String by Run-Length Counts, Keeping the Original When Not Shorter
Implement run-length string compression that replaces each run of repeated characters with the character and its count, returning the original string when the compressed form is not strictly shorter. Tests careful run handling, multi-digit counts, the tie rule, and complexity and edge-case discussion.
Coding & AlgorithmsOnsite - New RelicMediumBackend EngineerDesign a Kafka Consumer Service That Groups Trace Events by Trace ID
Design a distributed service that consumes trace events from Kafka, groups every event sharing a trace ID, and hands each complete trace to an existing processing function. Covers partitioning, in-memory versus external state, deciding when a trace is complete, and traces that stay open for hours.
System DesignOnsite - New RelicMediumBackend EngineerLongest Strictly Increasing Path in a Grid with Four-Directional Moves
Given an integer matrix, find the number of cells on the longest path whose values strictly increase, moving only up, down, left, or right with no diagonal steps and no wrap-around at the edges. Tests grid search and the ability to turn a working first solution into an efficient one.
Coding & AlgorithmsOnsite - NuroHardBackend EngineerDesign Webhooks and Metric Aggregation
Design a webhook delivery platform and vehicle telemetry aggregation system. The solution covers multi-tenant subscriptions, at-least-once delivery, retries, signing, DLQs, endpoint isolation, high-volume ingestion, stream processing, raw storage, rollups, alerting, late events, and downsampling.
System DesignOnsite - NuroHardBackend EngineerImplement BFS and a Job Scheduler
Solve grid reveal with BFS and design a thread-safe periodic job scheduler. The solution covers Minesweeper-style expansion, queue processing, priority-queue scheduling, locks, worker pools, cancellation, duplicate prevention, long-running tasks, clock drift, and backpressure.
Coding & AlgorithmsOnsite - OktaMediumBackend EngineerBuild and Review a Configurable Node.js Token-Bucket Rate Limiter
Implement a configurable Node.js Express token-bucket rate limiter with monotonic refill, HTTP 429 responses, code-review reasoning, and multi-instance limits.
Software Engineering FundamentalsOnsite - OktaMediumBackend EngineerDesign Cross-Domain SSO and OIDC Access to Third-Party Tools
Design cross-domain SSO with OIDC authorization-code flow, separate site sessions, secure account linking, third-party federation, and delegated API authorization.
System DesignOnsite - OktaMediumBackend EngineerDesign Single Sign-On Across Two Acquired Sites With OIDC Federation
Design cross-domain single sign-on after one company acquires a second site on a different domain, then extend it to many sites and to delegated API access for third-party tools, covering the authorization-code flow, session separation, and the authentication-versus-authorization distinction.
System DesignOnsitesystem-designauthenticationoidc - OktaMediumBackend EngineerRepair an Express Authentication Endpoint Without Blocking the Event Loop
Repair an Express authentication endpoint with input validation, asynchronous bcrypt, safe errors, correct HTTP status codes, and event-loop-aware resource controls.
Software Engineering FundamentalsOnsite - OracleMediumBackend EngineerAdd One to an Integer Stored as Digits Without ArrayList
This problem tests array manipulation skills and the ability to handle carry-over logic in fixed-size numerical representations.
Coding & AlgorithmsOnsiteArraysMathAlgorithms - OracleMediumBackend EngineerDesign a Distributed Rate Limiter
This problem tests the ability to design a scalable, low-latency distributed system for enforcing traffic quotas across multiple geographic regions with considerations for consistency and burst handling.
System DesignOnsiteDistributed SystemsRate LimitingScalability - OracleMediumBackend EngineerDesign a High-Volume Healthcare Data Ingestion Pipeline
This question tests the ability to design a resilient, high-throughput ETL pipeline for sensitive and messy healthcare data, focusing on fault isolation, data integrity, and architectural scalability.
System DesignOnsiteETLData PipelineScalability
Airbnb
Airwallex
Arm
Coinbase
Databricks
Harvey
Meta
Mintlify
Nuro
Okta
Oracle