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