Topic
System Design interview questions
1311 System Design questions from 230 companies, with hints, runnable code and solution walkthroughs.
60 easy819 medium432 hard
System Design interview questions by the numbers
Last updated
Katkat has 1,311 System Design interview questions from 230 companies; the most come from OpenAI (8%), Meta (5%) and Amazon (4%). By difficulty: 5% easy, 62% medium and 33% hard. The most common round is Onsite (55%). Frequent concepts include System Design, Distributed Systems, Scalability and Caching.
Companies (230)
Difficulty
- Easy5% · 60
- Medium62% · 819
- Hard33% · 432
Interview rounds
- Onsite55% · 721
- Technical Screen39% · 517
- Online Assessment3% · 38
- Other2% · 21
- HR Screen1% · 13
Roles
- Software Engineer91% · 1189
- Machine Learning Engineer2% · 31
- Data Engineer2% · 26
- Backend Engineer2% · 25
- Frontend Engineer1% · 19
Frequent concepts
- System Design31% · 400
- Distributed Systems24% · 316
- Scalability15% · 196
- Caching7% · 95
- Concurrency7% · 91
- system-design6% · 83
Most mentioned in interview experiences
- 1.Design delivery driver payment system3 reports
- 2.Debug round-robin request router2 reports
- 3.Design a basic bank system API2 reports
- 4.Design a delivery cost system2 reports
- 5.Design a Distributed Key-Value Store for a Small Company's Internal Use2 reports
- 6.Design a Donation System for a Three-Day Fundraising Campaign2 reports
- 7.Design a file search module like UNIX find2 reports
- 8.Design a Food Review System for a Delivery App, Focused on the Database Schema2 reports
- 9.Design a Job Scheduler for ML Training and Batch Inference on a Shared Cluster2 reports
- 10.Design a Menu Item Review and Rating System for a Food-Delivery Platform2 reports
Counted from 393 candidate interview experiences on Katkat. How we collect and count
Showing 871–900 of 1311 results
Design the backend for a live multiplayer riddle showdown where wrong or slow answerers are eliminated each round and large audiences spectate in real time. Tests room sharding, authoritative round settlement, mid-round crash recovery, and isolating spectator traffic from gameplay.
OpenAISoftware EngineerSystem DesignOnsiteDesign the backend for a multiplayer typing race where wrong keys lock a player out for 1.5 seconds. Covers authoritative match servers, the lockout mechanism, skill-based matchmaking, ratings and leaderboards, and compensating for network latency.
OpenAISoftware EngineerSystem DesignTechnical ScreenDesign an online trivia game where 2 to 8 players race to buzz in and answer each question correctly, and a wrong answer locks that player out for one second. Tests authoritative server design for real-time input, lockout state, matchmaking, and fairness across differing network latencies.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis question assesses the ability to architect a multi-tenant cloud IDE platform, focusing on secure runtime isolation, resource partitioning, and efficient state management for concurrent user environments.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis problem tests the design of a distributed, idempotent payment processing system that ensures data consistency and financial integrity across asynchronous state transitions.
OpenAISoftware EngineerSystem DesignOnsiteDesign a resilient merchant-side payment orchestration platform that routes transactions across multiple payment service providers (PSPs) while enforcing strict amount invariants, idempotent state transitions, and auditability.
OpenAISoftware EngineerSystem DesignOnsiteThis question tests the ability to design a reliable, fault-tolerant distributed system for handling financial transactions, focusing on idempotency, atomicity, and consistent state transitions.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis question tests the ability to design a distributed payment processing system that guarantees atomicity and consistency under high concurrency and partial network failures.
OpenAISoftware EngineerSystem DesignOnsiteThis question tests the ability to design a fault-tolerant payment system that handles distributed transactions, ensures idempotency, and reconciles state with external gateways.
OpenAISoftware EngineerSystem DesignTechnical ScreenDesign a hold-and-charge payment processor with honest asynchronous results, durable deduplication, incremental network batches, and safe acknowledgment recovery.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis system design question evaluates a candidate's ability to architect a reliable backend payment flow, including idempotent request handling, transactional data modeling, and reconciliation with external processors. It is commonly asked to assess practical distributed systems skills around failure handling, consistency, and scalability under real-world conditions, testing applied architectural reasoning rather than pure theory.
OpenAISoftware EngineerSystem DesignTechnical ScreenA system design interview question asking you to design a payment system that charges customers through an external payment provider. It tests exactly-once charging under retries and timeouts, payment state machines, ledger and reconciliation design, webhook handling, and failure recovery.
OpenAISoftware EngineerSystem DesignOnsiteDesign a payment system that places holds and captures final amounts, submits charges in batches, reconciles internal records against processor settlement reports, and never double-charges when calls are retried. It tests payment state machines, double-entry ledgers, idempotency and reconciliation.
OpenAISoftware EngineerSystem DesignOnsiteA system design question about a photo service that supports upload, download and delete while keeping only one stored copy of any content with the same SHA-256 hash. It tests content-addressed storage, reference tracking, safe deletion under concurrent uploads, and the security risks of deduplicating across users.
OpenAISoftware EngineerSystem DesignTechnical ScreenA system design question: build a real-time multiplayer typing race where players matched by language into races of 2 to 8 type the same text, see each other's progress and errors live, freeze for one second per error, and can be watched by spectators. It tests matchmaking, server-authoritative real-time state, fan-out to spectators and fairness under network latency.
OpenAISoftware EngineerSystem DesignTechnical ScreenDesign a real-time multiplayer typing race for 2 to 8 players in which the first player to type a generated passage wins and every wrong letter freezes that player for one second. The discussion covers the freeze mechanism, matchmaking, ranking players by score, and keeping races fair when players have different network delays.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis question tests your ability to design a low-latency, stateful distributed system that handles real-time bidirectional communication and ensures strict move consistency.
OpenAISoftware EngineerSystem DesignTechnical ScreenSystem design question about a real-time trivia battle royale in which dozens to a hundred or more players per room answer timed rounds, the wrong and slowest are eliminated, and spectators watch live leaderboards. It tests sharding by room, authoritative round settlement, fair answer timing, recovery from a server failure mid-round, and spectator isolation.
OpenAISoftware EngineerSystem DesignOnsiteDesign a reliable payment-processing service that prevents duplicate charges and preserves an auditable state history through retries and partial failures. Cover idempotency, exact money representation, timeout ambiguity, asynchronous callbacks, reconciliation, state transitions, partitioning, and operational controls.
OpenAISoftware EngineerSystem DesignOnsiteThis System Design question evaluates a candidate's ability to architect a scalable, durable real-time messaging system, testing skills in distributed systems, data modeling, API design, persistence versus low-latency delivery, ordering guarantees, missed-message recovery, notifications, and operational scaling.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis problem tests your ability to design a distributed, low-latency messaging system that handles concurrent message delivery, persistence, and synchronization across multiple devices.
OpenAISoftware EngineerSystem DesignTechnical ScreenA system design question about building a Sora-style text-to-video generation service in which every generation task runs on exactly one GPU. It tests task lifecycle and dispatch design, fair sharing of GPU time across many users, and cancellation of queued and running tasks, including whether a direct RPC to the worker is enough.
OpenAISoftware EngineerSystem DesignOnsiteThis problem tests your ability to design a distributed, asynchronous task processing system that balances resource fairness, reliability in the face of compute failures, and tiered prioritization.
OpenAISoftware EngineerSystem DesignTechnical Screen- Design a URL ShortenerMedium
This question tests your ability to design a highly scalable, distributed URL shortening service, focusing on database schema design, request routing, and efficient short-code generation.
OpenAISoftware EngineerSystem DesignOnsite This problem tests your ability to design a distributed, high-scale URL shortening service, focusing on data modeling, collision-resistant ID generation, and performance optimization via caching.
OpenAISoftware EngineerSystem DesignOnsiteDesign a distributed demand-response and curtailment controller for an electrical grid that sheds load during emergencies while strictly respecting user preferences, device criticalities, and fairness constraints.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis problem tests the ability to design an efficient search and constraint-solving system for crossword puzzles, requiring optimized data structures for prefix lookups and a backtracking strategy to handle search space pruning.
OpenAISoftware EngineerSystem DesignTechnical ScreenThis problem tests your ability to design a scalable, distributed architecture capable of solving large-scale constraint satisfaction problems (crossword filling) across a vast vocabulary.
OpenAISoftware EngineerSystem DesignTechnical ScreenDesign a fullstack app with frontend focus evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
OpenAISoftware EngineerSystem DesignTechnical ScreenA system design question about a metrics monitoring system that collects time series from services and hosts, stores them, serves dashboard queries and raises alerts. After a brief end-to-end sketch, the candidate goes deep on one or two areas, such as time-series storage, label cardinality, downsampling or reliable alert evaluation.
OpenAISoftware EngineerSystem DesignTechnical Screen