Practice.
Self-score.
Whiteboard practice for 15 canonical system design problems. Each exercise is prompt-only at first — hints are collapsible, rubric and red-flags are gated behind a "reveal" button. The goal: try it cold, then measure yourself against the rubric.
Communication
8 shippedWhatsApp — Chat at Planet Scale
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Notification System
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Video Conferencing
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Collaborative Whiteboard
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Gmail
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Google Calendar
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Reminder Alert
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Slack / Discord — Real-Time Messaging
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Financial & Trading
7 shippedBidding Platform
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Payment Gateway
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Crypto Exchange
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Google Ads
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Stock Exchange — Matching Engine
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Real-time Fraud Detection
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Stock Trading Platform
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Gaming
1 shippedInfrastructure
12 shippedDistributed Priority Queue
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Count Unique Active Users
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Distributed Job Scheduler
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Distributed Locking
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
CDN
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
ChatGPT
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Code Deployment Pipeline
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Distributed Cache
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
LeetCode
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Metrics & Monitoring
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Rate Limiter
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Unique ID Generator
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Marketplace & Booking
8 shippedTicketmaster — Event Ticketing
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Uber / Lyft — Ride Dispatch
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
E-Commerce Platform
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Airbnb
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
DoorDash / Uber Eats
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Flash Sale
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Shopping Cart
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
URL Shortener — bit.ly / TinyURL
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Media & Streaming
2 shippedSearch & Discovery
6 shippedGoogle Maps
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Google News
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Search Autocomplete
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Google Search — Web Search Engine
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Web Crawler
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Yelp / Google Places
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Social & Feed
10 shippedTop-K Leaderboard
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Reddit-Style Comments
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
LinkedIn MutualConnection Search
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Recommendation Algorithm
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Ad Click Aggregator
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Instagram / Photo + Reels Sharing
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Twitter / News Feed
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Twitter Trending
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
YouTube Likes Counter
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Storage & Data
6 shippedGoogle Docs / Live Collaborative Editor
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Amazon S3
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Distributed Logging Framework
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Dropbox Sync
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Google Drive / Dropbox
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.
Key-Value Store
Whiteboard exercise. Try the problem cold, then reveal the rubric to self-score.