Real-World Case Studies

Design real systems. 37+ case studies from beginner to FAANG-level — with architecture diagrams, capacity estimation, and detailed trade-off analysis.

Showing 37 case studies

Medium45 min

Design WhatsApp

Communication

WebSocketsMessage StorageEncryptionGroup Chats
Asked at:MetaGoogle
Medium35 min

Design a Notification System

Communication

Fan-outPriority QueuesPush/Email/SMSTemplating
Asked at:AmazonMeta
Medium40 min

Design Real-time Chat

Communication

PresenceTyping IndicatorsRead ReceiptsOrdering
Asked at:SlackDiscord
Hard50 min

Design Gmail

Communication

StorageSearchThreadingSpam Filtering
Asked at:Google
Hard55 min

Design Zoom

Communication

WebRTCMedia ServersScreen SharingRecording
Asked at:GoogleMicrosoft
Hard50 min

Design Twitter / X

Social

Tweet FanoutTimeline GenerationTrending TopicsPush vs Pull
Asked at:MetaGoogleAmazon
Hard45 min

Design Instagram

Social

Photo StorageCDNFeed GenerationStories
Asked at:MetaGoogle
Hard55 min

Design YouTube

Social

Video TranscodingCDN StreamingRecommendationsUpload Pipeline
Asked at:GoogleNetflix
Medium40 min

Design a News Feed

Social

Relevance RankingReal-time UpdatesAd Insertion
Asked at:MetaLinkedIn
Medium40 min

Design Reddit

Social

Post RankingComment TreesSubreddit ShardingVoting
Asked at:Reddit
Hard50 min

Design TikTok

Social

Video RecommendationShort-form ServingCreator Analytics
Asked at:ByteDanceMeta
Expert60 min

Design Amazon

E-commerce

Product CatalogueInventoryCartOrder ManagementPayment
Asked at:AmazonGoogle
Hard40 min

Design a Flash Sale System

E-commerce

Inventory ReservationOverselling PreventionQueue Checkout
Asked at:AmazonShopify
Hard50 min

Design Stripe

E-commerce

IdempotencyDouble-charge PreventionWebhooksReconciliation
Asked at:StripeSquare
Hard50 min

Design Airbnb

E-commerce

Geospatial SearchAvailability CalendarBooking Transactions
Asked at:AirbnbGoogle
Expert55 min

Design Uber

E-commerce

Driver MatchingReal-time GPSSurge PricingTrip Lifecycle
Asked at:UberGoogle
Easy25 min

Design a URL Shortener

Infrastructure

Hash GenerationCollision HandlingRedirectionAnalytics
Asked at:All Companies
Easy30 min

Design a Rate Limiter

Infrastructure

Token BucketSliding WindowDistributed Rate Limiting
Asked at:All Companies
Medium40 min

Design a Web Crawler

Infrastructure

URL FrontierPoliteness PolicyDeduplication
Asked at:GoogleMicrosoft
Medium45 min

Design a Key-Value Store

Infrastructure

Consistent HashingReplicationRead/Write Paths
Asked at:AmazonGoogle
Medium35 min

Design a Distributed Cache

Infrastructure

Consistent HashingEvictionReplication
Asked at:MetaGoogle
Hard55 min

Design a Search Engine

Infrastructure

CrawlingIndexingQuery ProcessingRanking
Asked at:GoogleMicrosoft
Expert55 min

Design Google Docs

Infrastructure

OT / CRDTReal-time CollaborationVersion History
Asked at:GoogleMicrosoft
Hard50 min

Design Kafka

Infrastructure

Log SegmentsConsumer GroupsReplicationCompaction
Asked at:LinkedInGoogle
Expert50 min

Design S3

Infrastructure

Bucket ShardingObject MetadataMultipart UploadConsistency
Asked at:Amazon
Hard40 min

Design a Job Scheduler

Infrastructure

Cron SemanticsExactly-once ExecutionDistributed Locking
Asked at:GoogleUber
Medium30 min

Design a Live Leaderboard

Real-time

Sorted SetsReal-time UpdatesFan-out
Asked at:Gaming Companies
Hard40 min

Design a Stock Ticker

Real-time

Low-latency StreamingOrdering GuaranteesReplay
Asked at:BloombergGoldman Sachs
Expert55 min

Design Google Maps

Real-time

QuadtreeGeohashingRouting AlgorithmsTraffic
Asked at:GoogleUber
Medium35 min

Design Nearby Friends

Real-time

Location StoragePrivacyGeospatial Queries
Asked at:MetaSnap
Hard50 min

Design DoorDash

Real-time

Order RoutingDriver AssignmentETA CalculationTracking
Asked at:DoorDashUber
Medium35 min

Design a CI/CD Pipeline

Developer

Build TriggersTestingArtifact StorageDeployment
Asked at:GoogleGitHub
Hard45 min

Design Heroku

Developer

Container BuildingBlue-green DeployRollbackEnvironments
Asked at:SalesforceAWS
Medium35 min

Design an API Gateway

Developer

RoutingRate LimitingAuthenticationAnalytics
Asked at:AmazonGoogle
Hard50 min

Design Datadog

Developer

Metric IngestionTime-series StorageAlertingDashboards
Asked at:DatadogGoogle
Hard45 min

Design Splunk

Developer

Log IngestionIndexingSearchRetention
Asked at:SplunkElastic
Medium30 min

Design Feature Flags

Developer

Targeting RulesRolloutKill SwitchA/B Integration
Asked at:LaunchDarklyMeta