Guided scenarios to build real intuition for distributed systems.
Beginner
URL Shortener
Design a URL shortener that handles 10,000 read requests per second with sub-10ms latency.
Order Notification Pipeline
When a customer places an order, send an email AND update inventory — reliably, even if one service is down.
Async Image Processor
Users upload images to S3. A pipeline resizes them to 3 sizes without blocking the upload response.
Event-Driven Inventory Sync
A warehouse uploads a CSV to S3 every hour. Three downstream systems (pricing, search, analytics) each need the changes — at their own pace, without blocking each other.
Intermediate
Fraud Detection System
Flag suspicious orders in real time without blocking the checkout flow. High traffic: 500 orders/s at peak.
Real-Time Leaderboard
A gaming leaderboard that serves 50,000 reads/s but only ~100 writes/s. Cost must be minimised.
E-Commerce Checkout
Your checkout service hammers RDS with Lambda connections and crashes on Black Friday. Fix it without touching the schema.
Auto-Scaling Web Tier
A traditional web app on EC2 fails under 10× traffic spikes. Redesign it to scale automatically without over-provisioning.
Advanced
Multi-Region Disaster Recovery
A region-wide AWS outage would take your API completely offline. Design for RTO < 1 min and RPO < 5 seconds.
Cost-Optimised Data Pipeline
Your nightly pipeline processes 50 GB of events and costs $800/month. Cut it to under $200 using the right AWS options — without changing the output.