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SYSTEM DESIGN · SAME IN EVERY COURSE

System Design Interview Course: One Decision at a Time

Design real systems one decision at a time: the building blocks, then Twitter, Uber, payments and more, the way interviews ask. Every lesson is interactive: you make each decision and the diagram grows with it. Free to start, no sign-up needed for the first screens.

Start with What Happens When You Open a Link 140 lessons · 14 chapters · Foundations free

Foundations

  1. What Happens When You Open a Link Free
  2. APIs Free
  3. Latency Numbers Free
  4. Back-of-the-Envelope Numbers Free
  5. Scaling Up vs Scaling Out Free
  6. The Interview Framework Free

Building Blocks

  1. Load Balancing
  2. Caching
  3. Eviction: LRU and LFU
  4. When Caches Go Wrong
  5. CDNs
  6. SQL or NoSQL
  7. Indexes
  8. Replication
  9. Sharding
  10. Consistent Hashing
  11. CAP and Consistency
  12. Message Queues
  13. Pub/Sub and Streams
  14. Rate Limiting
  15. Unique IDs
  16. Files and Object Storage
  17. Real-Time Updates
  18. Concurrency and Locks

Engineering Craft

  1. API Versioning
  2. Pagination
  3. Authentication and API Keys
  4. Idempotency Keys
  5. Webhooks
  6. Data Modeling
  7. Tables From Query Patterns
  8. Transactions and Isolation
  9. Timeouts, Retries, Circuit Breakers
  10. Monitoring and SLOs
  11. Safe Deployments
  12. Multi-Region and Disaster Recovery
  13. Networking Basics
  14. Consensus and Leader Election

Design: Read-Heavy & Counting

  1. Design a URL Shortener
  2. Rate Limiter
  3. Key-Value Store
  4. Distributed Counter
  5. Top K / Leaderboard

Design: Social & Feeds

  1. Twitter at Scale
  2. Instagram
  3. Reddit
  4. Live Comments

Design: Messaging & Real Time

  1. Chat (WhatsApp)
  2. Notification System

Design: Media & Files

  1. YouTube / Netflix
  2. Spotify
  3. Dropbox / Google Drive

Design: Search & Data

  1. Autocomplete
  2. Web Crawler
  3. Search Engine
  4. Ad Click Aggregator
  5. Metrics and Alerting

Design: Location

  1. Nearby Places (Yelp)
  2. Uber
  3. Google Maps
  4. Food Delivery (DoorDash)

Design: Booking & Money

  1. Ticketmaster
  2. Hotel Booking
  3. Flash Sale
  4. Payment System
  5. Digital Wallet
  6. Stock Exchange
  7. Online Auction (eBay)

Design: Infrastructure

  1. Message Queue (Kafka)
  2. Job Scheduler
  3. Google Docs

Design: Developer Tools

  1. Design LeetCode
  2. CI/CD (GitHub Actions)

Design: AI Systems

  1. ChatGPT
  2. Support Bot With RAG
  3. AI Code Assistant

Practice Problems

  1. Pastebin Free
  2. Image Hosting (Imgur) Free
  3. QR Code Service
  4. API Gateway
  5. Online Presence Indicator
  6. Web Analytics
  7. Like Counter
  8. CAPTCHA Service
  9. Facebook News Feed
  10. LinkedIn Feed
  11. Quora
  12. Stack Overflow
  13. Medium
  14. Pinterest
  15. Nested Comments
  16. Tagging Service
  17. Slack
  18. Discord
  19. Messenger
  20. Live Sports Scores
  21. Collaborative Whiteboard
  22. Video Calls (Zoom)
  23. Webhooks Service
  24. Email Service (Gmail)
  25. Reminders
  26. Calendar Invites
  27. Twitch
  28. TikTok
  29. Podcast Hosting
  30. E-Book Platform
  31. Video View Counts
  32. Craigslist
  33. E-Commerce Search
  34. Movie Reviews Aggregator
  35. Price Tracker
  36. Twitter Search
  37. Nearby Friends
  38. Transit Tracker
  39. Strava
  40. Weather Service
  41. Parking Spot Finder
  42. Airbnb
  43. Restaurant Reservations (OpenTable)
  44. Conference Rooms
  45. Movie Tickets
  46. Meeting Scheduler
  47. Coupons
  48. Amazon Checkout
  49. Shopify
  50. Inventory
  51. Order Tracking
  52. Splitwise
  53. Subscription Billing
  54. Load Balancer
  55. Log Collection
  56. Distributed Tracing
  57. Distributed Lock
  58. DNS
  59. Distributed File System
  60. Backups
  61. Image Generation Queue
  62. Translation Service
  63. Recommendations (Netflix)
  64. Content Moderation