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 631–660 of 1311 results
Design a check-and-insert service for about a million user IDs that reports whether an ID already exists and adds it if not. It tests memory estimates, data structure choice, atomic inserts under concurrency, trading memory for accuracy with compact filters, and durable on-disk storage with fast reads and writes.
MercorSoftware EngineerSystem DesignTechnical ScreenDesign a multi-tenant service that runs user-defined DAGs of automated steps (pre-processing, model pre-labeling, QA checks, exports), tracks every run, and survives crashes. Tests data modeling, separating the scheduler from workers, durable state, retries and idempotency, tenant fairness and observability.
MercorMachine Learning EngineerSystem DesignOnsiteDesign an event ticketing platform capable of handling flash-sale spikes without overselling, featuring transactional seat holds, idempotent payment processing, and virtual queueing.
MercorMachine Learning EngineerSystem DesignOnsiteTests your ability to architect a two-sided matching platform that enforces strict eligibility filters, dynamic availability tracking, multi-stage ranking with exploration, and closed-loop model evaluation.
MercorSoftware EngineerSystem DesignTechnical ScreenDesign an end-to-end personalized social feed system capable of serving low-latency ranked content while handling hybrid fanout, multi-stage ML candidate retrieval, and stable pagination.
MercorMachine Learning EngineerSystem DesignTechnical ScreenA system design question asking you to build a workflow system where users define multi-step workflows with dependencies, start runs, and track progress. It tests data modeling, orchestration and worker architecture, durable state, retries and idempotency, fairness between tenants, scaling and observability.
MercorMachine Learning EngineerSystem DesignOnsiteA system design question about an API that copies a dataset together with its tasks, model responses and grades so that the copy can be edited independently. It covers ID remapping, background jobs with progress tracking and resumable checkpoints, idempotent requests, worker leases, edits to the source during the copy, and cleanup after failure.
MercorSoftware EngineerSystem DesignTechnical ScreenThis question evaluates understanding of Kubernetes autoscaling mechanisms, external-to-pod traffic routing, and the differences between ReplicaSet and StatefulSet controllers.
MercorSoftware EngineerSystem DesignTechnical ScreenA payment endpoint calls an external provider to charge the customer and then writes a record to its own database. The question asks what can go wrong and how to redesign the flow, testing failure analysis for crashes and timeouts, safe retries, durable payment state, recovery through status checks, webhooks and reconciliation, and lock placement.
MercorSoftware EngineerSystem DesignTechnical ScreenThis 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 and optimize React performance issues states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
MetaSoftware EngineerSystem DesignTechnical ScreenThis problem evaluates your ability to translate product goals into actionable metrics and design a scalable, reliable data schema to support those metrics.
MetaData EngineerSystem DesignTechnical ScreenA system design question on ephemeral stories that followers can view for 24 hours before they disappear, covering media upload, the tray of accounts with unwatched stories, playback, and viewer tracking. It tests expiry semantics, fan-out for popular authors, watched-state storage, and media delivery.
MetaSoftware EngineerSystem DesignOnsiteThis problem tests the ability to design an inverted index system that supports complex logical queries, high-concurrency updates, and consistent pagination over a distributed dataset.
MetaSoftware EngineerSystem DesignOnsiteThis problem tests the design of a scalable inverted index system capable of handling boolean queries (AND/OR/NOT) over a high-throughput stream of user status updates.
MetaSoftware EngineerSystem DesignOnsiteThis question evaluates skills in designing scalable, low-latency real-time systems, including distributed architecture, concurrency control and ordering, data modeling, API design, and fault-tolerance for high-contention auction workloads.
MetaSoftware EngineerSystem DesignOnsiteDesign a high-scale real-time ride-hailing dispatch and trip lifecycle backend. The problem tests geospatial indexing, high-throughput location ingestion, concurrent driver assignment without double-booking, and idempotent distributed state management.
MetaSoftware EngineerSystem DesignOnsiteThis question tests the ability to design a scalable web crawler capable of handling billions of pages while maintaining freshness and avoiding redundant work.
MetaSoftware EngineerSystem DesignTechnical ScreenDesign a Dropbox-like file storage and sync service 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.
MetaSoftware EngineerSystem DesignOnsiteA system design interview question asking you to build a GPS fitness-tracking app in the style of Strava, where athletes record runs and rides, save routes and follow friends' activity feeds. It tests offline-tolerant recording, duplicate-free uploads, storage for large GPS tracks, feed fan-out and privacy controls.
MetaSoftware EngineerSystem DesignOtherDesign a Messenger-style chat backend for one-to-one conversations without WebSockets or other persistent connections, using only request/response web APIs. Tests message ordering, idempotent sends, cursor-based sync, cheap polling, push wake-ups, multi-device delivery and failure handling at very large scale.
MetaSoftware EngineerSystem DesignOnsiteA system design question on a notification platform that takes events from many product services and delivers them to users through push and in-app channels. It tests ingestion contracts, preference checks, grouping and rate limiting, priority isolation, third-party push delivery, and deduplication under retries.
MetaSoftware EngineerSystem DesignOnsiteA system design question on recommending people a user may know on a large social network, from candidate generation through ranking and serving. It tests graph-based candidate sourcing, batch versus real-time freshness, ranking signals and labels, filtering, privacy, cold start, and evaluation.
MetaSoftware EngineerSystem DesignOnsiteA system design question on building the home news feed of a large social network: publishing posts and serving each user a ranked, paginated feed of posts from the accounts they follow. It tests fan-out strategy, accounts with huge follower counts, ranking under a latency budget, and correctness for deletes and privacy.
MetaSoftware EngineerSystem DesignOnsiteA system design question on a real-time chat service with one-to-one and group conversations, instant delivery to online users, offline catch-up, and history across devices. It tests connection routing, per-conversation ordering, idempotent sends, message storage, group fan-out, and read receipts.
MetaSoftware EngineerSystem DesignOnsiteA two-phase security engineering design prompt from Meta: design a browser-based collaborative coding pad with real-time co-editing, code execution and session playback, then threat-model your own architecture. It tests concurrent editing, sandboxing untrusted code, access control, tenant isolation and risk prioritization.
MetaSecurity EngineerSystem DesignOnsiteThis question evaluates a candidate's ability to design a large-scale, real-time data processing system that continuously scores and ranks trending content under strict freshness constraints. It tests system design skills including stream processing, time-decayed scoring, and handling high write throughput at scale. This type of question is commonly used to assess architectural thinking for systems balancing timeliness, popularity, and novelty signals.
MetaSoftware EngineerSystem DesignOnsiteDesign an enterprise-scale notification platform supporting multi-channel delivery, recipient fanout, preference filtering, and resilient at-least-once delivery guarantees.
MetaSoftware EngineerSystem DesignOnsiteThis question tests the ability to design a high-throughput, distributed system that maintains a real-time ranking of the most popular items across a massive global user base.
MetaSoftware EngineerSystem DesignOnsiteThis question evaluates a candidate's understanding of distributed systems architecture, media processing and delivery concepts including upload resiliency, transcoding into multiple bitrates, scalable storage and low-latency streaming.
MetaSoftware EngineerSystem DesignOnsiteDesign a bank system with scheduling and rankings 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.
MetaSoftware EngineerSystem DesignTechnical Screen