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System Design 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
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- 11
- Topics
- 8
- Languages
Showing 631–660 of 1311 results
- MercorMediumSoftware EngineerCheck-and-Insert for a Million User IDs: Balancing Latency, Memory and Accuracy
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.
System DesignTechnical Screen - MercorMediumMachine Learning EngineerDesign a DAG Pipeline Runner for Data-Labeling Jobs
Design 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.
System DesignOnsiteworkflow-orchestrationdistributed-systemsstate-machines - MercorMediumMachine Learning EngineerDesign a High-Demand Event Ticket Marketplace
Design an event ticketing platform capable of handling flash-sale spikes without overselling, featuring transactional seat holds, idempotent payment processing, and virtual queueing.
System DesignOnsitesystem-designdistributed-systemsconcurrency - MercorMediumSoftware EngineerDesign a Project-to-Contractor Matching System
Tests 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.
System DesignTechnical Screensystem-designmatching-enginerecommendation-systems - MercorEasyMachine Learning EngineerDesign a Social Feed
Design 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.
System DesignTechnical Screensystem-designfeed-rankingrecommendation-systems - MercorMediumMachine Learning EngineerDesign a workflow orchestration system that runs multi-step jobs reliably
A 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.
System DesignOnsite - MercorMediumSoftware EngineerDesign an API to Deep-Copy a Dataset with Its Tasks, Model Responses and Grades
A 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.
System DesignTechnical Screen - MercorMediumSoftware EngineerExplain Kubernetes autoscaling and traffic routing
This question evaluates understanding of Kubernetes autoscaling mechanisms, external-to-pod traffic routing, and the differences between ReplicaSet and StatefulSet controllers.
System DesignTechnical Screen - MercorMediumSoftware EngineerMake a Charge-Then-Record Payment Endpoint Safe Against Timeouts, Retries and Crashes
A 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.
System DesignTechnical Screen - MetaMediumSoftware EngineerDebug and optimize React performance issues
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 and optimize React performance issues states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
System DesignTechnical Screen - MetaMediumData EngineerDefine metrics and data model for product features
This problem evaluates your ability to translate product goals into actionable metrics and design a scalable, reliable data schema to support those metrics.
System DesignTechnical ScreenData ModelingProduct AnalyticsMetrics - MetaMediumSoftware EngineerDesign 24-Hour Ephemeral Stories for a Photo and Video Sharing App
A 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.
System DesignOnsite - MetaHardSoftware EngineerDesign Boolean Search for Status Posts
This 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.
System DesignOnsiteInverted IndexSearchDistributed Systems - MetaMediumSoftware EngineerDesign Boolean Search over User Status Posts
This 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.
System DesignOnsiteInverted IndexBoolean SearchConcurrency - MetaMediumSoftware EngineerDesign Real-Time Auctions for Social Posts
This 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.
System DesignOnsite - MetaHardSoftware EngineerDesign Ride Requests, Driver Matching, and Trip State
Design 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.
System DesignOnsiteDistributed SystemsGeospatialConcurrency - MetaMediumSoftware EngineerDesign Search And Web Crawling Systems
This question tests the ability to design a scalable web crawler capable of handling billions of pages while maintaining freshness and avoiding redundant work.
System DesignTechnical ScreenDistributed SystemsWeb CrawlingScalability - MetaHardSoftware EngineerDesign a Dropbox-like file storage and sync service
Design 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.
System DesignOnsite - MetaMediumSoftware EngineerDesign a GPS Fitness Tracking App with Activity Uploads and a Friends Feed
A 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.
System DesignOther - MetaMediumSoftware EngineerDesign a Messenger-Style Chat Backend Without WebSockets or Persistent Connections
Design 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.
System DesignOnsite - MetaMediumSoftware EngineerDesign a Notification System That Delivers Events to Users at Scale
A 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.
System DesignOnsite - MetaMediumSoftware EngineerDesign a People-You-May-Know Friend Recommendation System
A 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.
System DesignOnsite - MetaMediumSoftware EngineerDesign a Ranked Home News Feed for a Large Social Network
A 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.
System DesignOnsite - MetaMediumSoftware EngineerDesign a Real-Time Chat Service for One-to-One and Group Messaging
A 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.
System DesignOnsite - MetaMediumSecurity EngineerDesign a Real-Time Collaborative Coding Interview Pad, Then Threat-Model It
A 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.
System DesignOnsite - MetaMediumSoftware EngineerDesign a Real-Time Trending Hashtags System
This 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.
System DesignOnsite - MetaMediumSoftware EngineerDesign a Reliable Notification System
Design an enterprise-scale notification platform supporting multi-channel delivery, recipient fanout, preference filtering, and resilient at-least-once delivery guarantees.
System DesignOnsiteDistributed SystemsMessage QueuesScalability - MetaMediumSoftware EngineerDesign a Top-K trending items service
This 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.
System DesignOnsiteDistributed SystemsData StreamsCaching - MetaMediumSoftware EngineerDesign a YouTube/Netflix video platform
This 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.
System DesignOnsite - MetaHardSoftware EngineerDesign a bank system with scheduling and rankings
Design 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.
System DesignTechnical Screen
Mercor
Meta