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11 questions à lire maintenant, sans compte.
QuestionIndice d'entrepriseConceptsAccès
- 01Ad Click AggregatorDesign an ad click aggregation system that ingests millions of click events per second and serves near-real-time plus historical aggregate metrics to advertisers.MetaStreaming Windowed AggregationIdempotency Key+1Guide gratuit
- 02DropboxDesign Dropbox — a cloud file storage and synchronization service where users upload large files and keep them in sync across devices and shared folders.—Chunked Transfer + Content-Hash DedupConflict-Free Collaboration (OT/CRDT)+1Guide gratuit
- 03Facebook MessengerDesign Facebook Messenger — a real-time chat system delivering messages with low latency, ordering guarantees, and multi-device sync at massive scale.MetaPersistent Connection ManagementPub/Sub Fan-out+1Guide gratuit
- 04TicketmasterDesign Ticketmaster — an event ticketing system that sells reserved seats under extreme flash-sale contention without ever double-selling a seat.—Reservation Hold with TTLVirtual Queue / Admission Control+2Guide gratuit
- 05TinderDesign Tinder — a location-based dating app with swipe feeds, mutual-match detection, and recommendation of nearby profiles.—Geospatial IndexingProbabilistic Data Structures+1Guide gratuit
- 06Top K Songs (Spotify)Design Spotify's Top-K most-played songs feature — compute top charts over sliding time windows at listening-event scale.Spotify / MetaStreaming Windowed AggregationProbabilistic Data Structures+2Guide gratuit
- 07Uber (Ride Hailing)Design Uber — a ride-hailing platform matching riders to nearby drivers in real time, with live location tracking, pricing, and trip lifecycle management.UberGeospatial IndexingOptimistic Concurrency Control+1Guide gratuit
- 08Web CrawlerDesign a web-scale crawler that politely fetches and indexes billions of pages, deduplicates content, and keeps the corpus fresh.GoogleProbabilistic Data StructuresAsync Job Queue+2Guide gratuit
- 09URL ShortenerDesign a scalable URL shortener for 100M daily active users.InstagramCache-Aside and Stampede ControlSharding and Hot-Key MitigationGuide gratuit
- 10LLM Inference GatewayDesign an LLM inference gateway that sits between internal product teams and multiple model providers/backends, handling routing, streaming, quotas, and safety controls at company scale.OpenAI / AnthropicMulti-Provider Routing / FailoverVirtual Queue / Admission Control+2Guide gratuit
- 11AI Customer Support AgentDesign an AI customer support agent for a SaaS product.—Agentic Tool-Calling LoopRAG Grounding and Citation+2Guide gratuit
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QuestionIndice d'entrepriseConceptsAccès
- 12AI Agent SystemDesign a production AI agent application platform that accepts user goals, manages context and memory, calls tools safely, pauses for human review when needed, and improves through traces and evals.—Agentic Tool-Calling LoopHuman-in-the-Loop Review+1Aperçu
- 13Auction (eBay)Design an eBay-style auction system — bidders compete on live listings under heavy contention near closing time, and the system must never accept a losing bid as the winner or let an auction close...eBayOptimistic Concurrency ControlState Machine + Idempotent Transitions+1Aperçu
- 14Chat AppDesign the client-side architecture of a WhatsApp-style mobile messenger — connection handling, message state, offline storage, and encryption all have to survive a flaky mobile network.DiscordPersistent Connection ManagementState Machine + Idempotent Transitions+1Aperçu
- 15Chat ServiceDesign the backend infrastructure behind a chat product — stateful connection servers, message storage, and group fan-out — for hundreds of millions of concurrent users.DiscordPersistent Connection ManagementPub/Sub Fan-out+1Aperçu
- 16Collaborative ShoppingDesign a collaborative shopping experience where multiple people share a single cart in real time, add and remove items concurrently, and one designated participant checks out on behalf of the group.—Conflict-Free Collaboration (OT/CRDT)Reservation Hold with TTL+2Aperçu
- 17Coupons and Deals PlatformDesign a coupons and deals platform where users browse and search a large, frequently changing catalog of deals and redeem coupon codes exactly once per limit, without ever letting stale prices or...—Cache-Aside and Stampede ControlIdempotency Key+1Aperçu
- 18Donation PlatformDesign a donation platform like GoFundMe — a campaign can go viral overnight and receive a massive spike of small donations, and every dollar must be captured, refundable, and reflected in an...—Virtual Queue / Admission ControlAsync Job Queue+1Aperçu
- 19Facebook Post SearchDesign search over a social feed — let users find posts by keyword in near real time while respecting each post’s privacy/visibility settings.MetaInverted Index SearchAccess Control Filtering (ACL)+1Aperçu
- 20Flash SaleDesign a flash sale system where a limited quantity of a hot item goes on sale at a fixed instant and receives a 1000x traffic spike in seconds — inventory must never oversell, and most users should...—Atomic Counter InventoryVirtual Queue / Admission Control+2Aperçu
- 21Flight Booking SystemDesign a flight booking system that lets travelers search and book multi-leg itineraries across airlines, reserving fare-class seat inventory and issuing tickets without double-selling a seat or...DuffelReservation Hold with TTLSaga / Compensating Transaction+1Aperçu
- 22Game LeaderboardDesign a real-time game leaderboard that ranks millions of players by score, supports regional and time-windowed boards, and serves both top-N and a given player’s rank cheaply.StravaTop-K RankingSharding and Hot-Key Mitigation+1Aperçu
- 23Google DocDesign Google Docs’ real-time collaborative editing — multiple users typing in the same document simultaneously and seeing each other’s edits converge correctly.GoogleConflict-Free Collaboration (OT/CRDT)Persistent Connection Management+1Aperçu
- 24Google DriveDesign Google Drive as a permissioned file platform — folder hierarchies, shared drives, and access control that scale across billions of files and third-party integrations.GoogleAccess Control Filtering (ACL)Metadata/Data Separation+1Aperçu
- 25Hotel Reservation (Booking.com)Design Booking.com — a hotel marketplace aggregating live availability and pricing from thousands of independent supplier hotels, where search results must stay fast even though the underlying...Booking.comMulti-Provider Routing / FailoverCache-Aside and Stampede Control+2Aperçu
- 26Hotel ReservationDesign a single-chain hotel reservation engine — travelers search date-range availability across properties, place a hold, and confirm a booking without ever overbooking a room type past the chain’s...—Reservation Hold with TTLState Machine + Idempotent TransitionsAperçu
- 27Job SchedulerDesign a distributed job scheduler (a cron-as-a-service system) that lets tenants register recurring and one-off jobs, guarantees each job fires close to its scheduled time, and survives worker and...AirbnbResource Scheduling and PreemptionDistributed Lock / Lease Fencing+1Aperçu
- 28Metric Monitoring and AlertingDesign the metrics pipeline behind a monitoring platform — the path from an SDK on thousands of hosts emitting numeric measurements, through streaming pre-aggregation, into durable time-series...UberStreaming Windowed AggregationSharding and Hot-Key Mitigation+1Aperçu
- 29Moderation ServiceDesign a content moderation pipeline that screens user-submitted posts/media for policy violations, balancing posting latency against review accuracy at platform scale.LinkedInHuman-in-the-Loop ReviewAsync Job Queue+1Aperçu
- 30Monitoring and AlertingDesign the alerting and observability layer of a monitoring platform — the system that evaluates rules against incoming signals, decides who gets paged, and keeps on-call humans from drowning in...—Streaming Windowed AggregationNotification Delivery and RoutingAperçu
- 31NetflixDesign Netflix’s video delivery system — stream a licensed, curated catalog to tens of millions of concurrent viewers worldwide with minimal buffering and consistent quality.—Edge Caching / CDNMulti-Provider Routing / Failover+1Aperçu
- 32Payment SystemDesign a payment system for an e-commerce product — money must move correctly between buyer, platform, and seller even when networks fail mid-transaction, and every dollar must be traceable after the...StripeDouble-Entry LedgerIdempotency Key+2Aperçu
- 33Recommendation SystemDesign a large-scale personalized recommendation system for feed/video/ads.Netflix / MetaMulti-Stage Ranking FunnelTwo-Tower Retrieval+2Aperçu
- 34Restaurant ReservationDesign an OpenTable-style restaurant reservation system where diners book a time slot and party size at a restaurant, restaurants optimize table assignment, and no-shows are handled without requiring...YelpReservation Hold with TTLNotification Delivery and RoutingAperçu
- 35Robinhood (Stock Trading)Design a retail stock trading platform like Robinhood that lets millions of users place buy/sell orders, tracks cash and positions with regulatory-grade accuracy, and streams live quotes without ever...RobinhoodDouble-Entry LedgerState Machine + Idempotent Transitions+2Aperçu
- 36Search Bar AutocompleteDesign the autocomplete/typeahead system behind a search bar that returns the top-K query suggestions for a partial prefix within a sub-50ms budget, at the scale of a major search engine.MetaPrecomputed Read ViewTop-K Ranking+2Aperçu
- 37Spend Management SystemDesign a corporate spend management platform like Brex or Ramp — every card swipe must be authorized or declined against a live policy engine in under two seconds, and every transaction must flow...BrexReal-Time Rules/Policy EngineReconciliation / Background Repair+2Aperçu
- 38StripeDesign Stripe itself — a payments platform that other companies build on top of, exposing charge/webhook APIs to thousands of merchants while routing transactions across multiple underlying card...—Double-Entry LedgerIdempotency Key+2Aperçu
- 39Technical Deep DivePresent a technical deep dive of a system you personally built — the format used in senior/staff interview loops where you narrate one project end to end and defend your decisions under questioning.—Latency Budget DecompositionCapacity Estimation and Scale SizingAperçu
- 40Ticketmaster (General Admission)Design Ticketmaster for general-admission events — there is no seat map, only a fixed capacity count per ticket tier, and the system must sell tickets correctly under extreme flash-sale contention...TicketmasterAtomic Counter InventoryVirtual Queue / Admission Control+1Aperçu
- 41TikTokDesign TikTok’s For You feed — rank and serve an endless short-video feed personalized per user without relying on who they follow.ByteDanceMulti-Stage Ranking FunnelPrecomputed Read View+1Aperçu
- 42WebhookDesign a webhook delivery platform (Stripe-webhooks-style) that reliably delivers event notifications to thousands of third-party consumer endpoints under retry, ordering, and security constraints.StripeIdempotency KeyRetry with Backoff + Dead-Letter+1Aperçu
- 43YelpDesign Yelp — a local business search and review platform that returns nearby, filterable business results ranked by relevance and rating.—Geospatial IndexingCache-Aside and Stampede Control+1Aperçu
- 44YouTubeDesign YouTube’s upload and processing pipeline — accept massive volumes of user-generated video uploads and transform them into a playable, multi-resolution catalog.—Chunked Transfer + Content-Hash DedupAsync Job Queue+2Aperçu
- 45RAG Knowledge AssistantDesign an enterprise RAG knowledge assistant that answers employee questions over internal documents (wikis, tickets, contracts) with grounded, cited answers while respecting per-document access...OpenAIRAG Grounding and CitationANN Vector Index+2Aperçu
- 46AI Training ClusterDesign the scheduler for a large GPU/TPU training cluster shared by multiple teams running distributed training jobs, handling gang scheduling, preemption, and failure recovery.MetaResource Scheduling and PreemptionRate Limiting / QuotaAperçu
- 47MCP Tool GatewayDesign an MCP-style tool gateway that lets AI agents discover and invoke enterprise tools (CRM writes, ticketing, internal APIs) safely, with per-user authorization and auditability.AnthropicAgentic Tool-Calling LoopAccess Control Filtering (ACL)+2Aperçu
- 48Ad Ranking Evaluation FrameworkDesign an evaluation framework for an ad ranking system.MetaOffline/Online Evaluation and A/B TestingBias Correction (Position/Counterfactual)Aperçu
- 49Rate LimiterDesign a distributed API rate limiter for a public API platform.CloudflareRate Limiting / QuotaSharding and Hot-Key MitigationAperçu
- 50Notification SystemDesign a multi-channel notification system that sends email, push, SMS, and in-app notifications on behalf of many internal services, respecting user preferences and delivery guarantees.UberNotification Delivery and RoutingIdempotency Key+1Aperçu
- 51ML Feature StoreDesign an ML feature store that serves the same features to both offline model training and low-latency online inference for a company like Uber.UberFeature Store / Point-in-Time CorrectnessAsync Job QueueAperçu
- 52Vector DatabaseDesign the storage and query engine of a vector database that indexes billions of embeddings for approximate nearest-neighbor search.Meta (Faiss)ANN Vector IndexSharding and Hot-Key MitigationAperçu
- 53ML Model Serving PlatformDesign a general-purpose ML model serving platform for non-LLM prediction serving used by many teams.NVIDIAFeature Store / Point-in-Time CorrectnessElastic Worker AutoscalingAperçu
- 54News Feed RankingDesign the ranking system for a social news feed like Instagram or Facebook.Meta (Instagram)Multi-Stage Ranking FunnelTwo-Tower Retrieval+2Aperçu
- 55Fraud DetectionDesign a real-time ML fraud/risk scoring system that scores payment transactions in under 100 ms.StripeReal-Time Rules/Policy EngineStreaming Windowed Aggregation+2Aperçu
- 56ETA PredictionDesign an ETA prediction service that returns arrival-time estimates for millions of trips per second.UberFeature Store / Point-in-Time CorrectnessLatency Budget Decomposition+1Aperçu
- 57Visual / Multimodal SearchDesign a visual and multimodal search system that retrieves visually similar images (and text-to-image matches) from a catalog of billions.PinterestTwo-Tower RetrievalANN Vector Index+1Aperçu
- 58LLM Guardrails PipelineDesign a guardrails pipeline that wraps an LLM application with layered input and output safety.NVIDIA / MetaLLM Safety GuardrailsReal-Time Rules/Policy EngineAperçu
- 59IoT Device PlatformDesign a platform managing ~10 million connected devices over MQTT: connection lifecycle and disconnect detection, telemetry ingest at fleet scale, and — the signature problem — reliably delivering...—Persistent Connection ManagementNotification Delivery and Routing+2Aperçu
- 60Distributed Key-Value StoreDesign a Dynamo-style highly available key-value store: partition keys across nodes with consistent hashing, replicate each key to N nodes, and let every operation tune its own consistency with...—Quorum Replication and FailoverSharding and Hot-Key Mitigation+1Aperçu
- 61LLM Evaluation PlatformDesign the evaluation platform for an organization shipping LLM features: manage a versioned golden set (stratified production samples, an adversarial library, constructed edge cases, and replays of...—Offline/Online Evaluation and A/B TestingBias Correction (Position/Counterfactual)+1Aperçu
- 62Real-time Voice AI AgentDesign a real-time voice AI agent platform for phone support and voice assistants: the complete loop from the user speaking to the agent speaking back.—Latency Budget DecompositionPersistent Connection Management+1Aperçu
- 63Stock ExchangeDesign the core trading system of a stock exchange: accept orders into a central limit order book, match at price-time priority, and when your own book cannot complete an order, finish the job across...—State Machine + Idempotent TransitionsIdempotency Key+2Aperçu
- 64Distributed CacheDesign a distributed in-memory cache service at Redis/Memcached scale that serves roughly 1M QPS at p99 under 5ms.MetaCache-Aside and Stampede ControlSharding and Hot-Key Mitigation+1Aperçu
- 65Distributed Message QueueDesign a Kafka-style durable, partitioned log broker that ingests high-throughput event streams.Apache Kafka (LinkedIn)Sharding and Hot-Key MitigationQuorum Replication and FailoverAperçu
- 66Object StorageDesign an S3-like object storage service that stores billions of immutable blobs durably and cheaply.Amazon / BackblazeMetadata/Data SeparationQuorum Replication and Failover+1Aperçu
- 67Food Delivery MarketplaceDesign a DoorDash-style food delivery marketplace connecting consumers, Dashers, and merchants.UberState Machine + Idempotent TransitionsGeospatial Indexing+1Aperçu
- 68Real-time Multiplayer GameDesign an authoritative server for a real-time multiplayer game.Riot GamesPersistent Connection ManagementOptimistic Local Update + ReconciliationAperçu
- 69Live CommentsDesign a live comments system that fans out comments from one live event to millions of concurrent viewers in real time.MetaPub/Sub Fan-outSharding and Hot-Key Mitigation+2Aperçu
- 70Online JudgeDesign a LeetCode-style online judge that safely runs untrusted user code at scale.Google / AmazonAsync Job QueueSandboxed Execution+1Aperçu