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Real-time System Design Case Studies

InterviewSkool tracks 51 Real-time case studies with architecture diagrams, scale estimates, and deep dives.

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Companies

Topics

Distributed Systems 90Real-time 51Storage 43Data Pipelines 42API Design 41Databases 38Caching 37Security 32AI / ML 23Algorithms 20Scheduling 20Search 19Event Driven 14Fintech 14Payments 11Geospatial 11Analytics 11Observability 11E-commerce 11Messaging 10CDN 9Concurrency 8Ads 8Frontend 8Booking System 6Networking 5IoT 4Media 3Media Streaming 3Collaboration 3Rate Limiting 2
Real-timeClear all
Gaming Leaderboard (Top K)
16 min readDistributed SystemsReal-timeStorage
Beginner▶ Mock
Live Streaming (Instagram Live/YouTube Live)
14 min readMedia StreamingCDNReal-time
Beginner—▶ Mock
Push Notification Service
17 min readReal-timeMessagingDistributed Systems
Advanced+5▶ Mock
Messenger App
9 min readReal-timeMessagingDistributed Systems
Advanced+5▶ Mock
Shazam
14 min readSearchReal-timeAlgorithms
Advanced—▶ Mock
Live Location Sharing App
4 min readGeospatialReal-timeDistributed Systems
Beginner—▶ Mock
Snap Map Design
5 min readGeospatialReal-timeDistributed Systems
Beginner—▶ Mock
BookMyShow
9 min readDistributed SystemsPaymentsBooking System
Beginner▶ Mock
Uber Design (Ride-Hailing)
5 min readGeospatialReal-timeDistributed Systems
Advanced+2▶ Mock
Ad Click and Impression Aggregator
6 min readAdsAnalyticsData Pipelines
Advanced+2▶ Mock
Ad Frequency Capping Service (Netflix Ads)
7 min readAdsReal-timeCaching
Advanced▶ Mock
Ad Budget Pacing System
5 min readAdsReal-timeDistributed Systems
Advanced▶ Mock
Ads Audience Targeting System
5 min readAdsData PipelinesCaching
Advanced▶ Mock
Autonomous Vehicle Camera Perception Pipeline
5 min readAI / MLReal-timeConcurrency
Advanced▶ Mock
ChatGPT-Style Conversational AI Service
7 min readAI / MLReal-timeDistributed Systems
Advanced+2▶ Mock
User Behavior Tracking (Clickstream Analytics)
6 min readAnalyticsData PipelinesReal-time
Intermediate▶ Mock
Coffee Ordering System with Real-Time Notifications
6 min readE-commerceReal-timeAPI Design
Beginner▶ Mock
Real-Time Collaborative Editor (Google Docs / Sheets)
7 min readCollaborationReal-timeDistributed Systems
Advanced▶ Mock
Content Moderation System (Harmful Post Detection)
6 min readAI / MLSecurityData Pipelines
Advanced▶ Mock
Credit Card Authorization, Limits and Reporting
4 min readFintechPaymentsReal-time
Advanced▶ Mock
Daily Puzzle Platform (Wordle-style)
3 min readAPI DesignCachingDatabases
Beginner▶ Mock
Real-Time Data Stream Processor
4 min readData PipelinesReal-timeDistributed Systems
Intermediate▶ Mock
911 Emergency Call Routing Platform
5 min readReal-timeDistributed SystemsGeospatial
Advanced▶ Mock
Fitness Tracking App (Strava-style)
3 min readGeospatialStorageAPI Design
Intermediate▶ Mock
Food and Quick-Commerce Delivery Platform (Uber Eats / DoorDash)
6 min readGeospatialReal-timeE-commerce
Advanced▶ Mock
Interactive SQL Query Notebook (Snowflake)
4 min readAPI DesignSchedulingStorage
Intermediate▶ Mock
IoT / Sensor Telemetry Pipeline
7 min readIoTData PipelinesStorage
Intermediate+1▶ Mock
Scalable Likes System and Like Counter
5 min readDistributed SystemsCachingDatabases
Intermediate▶ Mock
Live Comments for Live Video (Facebook Live / TikTok Live)
6 min readReal-timeMessagingDistributed Systems
Intermediate▶ Mock
Malicious IP and URL Detection Service
5 min readSecurityReal-timeCaching
Advanced▶ Mock
Real-Time Market Data Distribution and VWAP (Bloomberg)
5 min readFintechReal-timeDistributed Systems
Advanced▶ Mock
Streaming Mention Analytics with Search and Alerts (Bloomberg)
3 min readReal-timeSearchAnalytics
Advanced▶ Mock
Metrics Monitoring and Alerting System
7 min readObservabilityData PipelinesStorage
Advanced+3▶ Mock
Real-Time Online Auction (eBay / Live Auctions)
7 min readReal-timeDistributed SystemsPayments
Advanced▶ Mock
Online Chess Platform (chess.com)
6 min readReal-timeDistributed SystemsMessaging
Intermediate▶ Mock
Online Judge and Coding Contest Platform (LeetCode)
6 min readDistributed SystemsSecurityScheduling
Intermediate▶ Mock
Perishable-Goods Inventory and Location Tracking
3 min readE-commerceDatabasesEvent Driven
Intermediate▶ Mock
"Played by Your Friends" Social Summary (Roblox)
3 min readDistributed SystemsCachingReal-time
Intermediate▶ Mock
Smart Grid Control over Unreliable Devices
7 min readIoTDistributed SystemsReal-time
Advanced▶ Mock
AI Prompt Playground (OpenAI / Anthropic Console)
6 min readAI / MLFrontendStorage
Intermediate▶ Mock
Security Monitoring Framework for Cloud Infrastructure
4 min readSecurityObservabilityData Pipelines
Advanced▶ Mock
Data Engineering for a Short-Video App (TikTok-scale)
4 min readData PipelinesAnalyticsStorage
Advanced▶ Mock
Smartwatch Sensor Subsystem Design
4 min readIoTReal-timeData Pipelines
Intermediate▶ Mock
Stock Price Alert System
3 min readFintechReal-timeAlgorithms
Intermediate▶ Mock
Stock Trading Platform (Zerodha / Robinhood)
6 min readFintechPaymentsReal-time
Advanced▶ Mock
Surge (Dynamic) Pricing for Ride-Hailing
4 min readReal-timeGeospatialAlgorithms
Advanced▶ Mock
To-Do List Service (REST API and Real-Time Shared Lists)
5 min readAPI DesignReal-timeCollaboration
Beginner▶ Mock
Top-K Trending Items (Heavy Hitters)
7 min readAnalyticsReal-timeAlgorithms
Advanced+4▶ Mock
User Activity Collection and Recent-Window Queries
5 min readAnalyticsData PipelinesStorage
Intermediate▶ Mock
Virtual Credit Card Service (Capital One)
6 min readFintechPaymentsSecurity
Intermediate▶ Mock
Human Avoidance for Autonomous Warehouse Robots
4 min readReal-timeAI / MLIoT
Advanced▶ Mock

Frequently Asked Questions

What is Real-time in system design?

Real-time is a core system design topic covered in 51 case studies on InterviewSkool. It appears frequently in FAANG interviews, especially at Google, Amazon, and Meta.

How should I prepare Real-time for system design interviews?

Study the case studies above, focusing on architecture trade-offs, scale estimates, and API designs. Practice explaining your decisions aloud — this is exactly what interviewers evaluate.

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