Design Challenges
Every challenge ends in a Production Readiness Review: your design runs against real traffic and injected failures, and the grade is based on what actually happened.
Design a URL Shortener
Greenfield PRRintrofreeDesign a URL shortener serving 5,000 redirects/sec with a 100:1 read/write ratio. Survive a viral-link traffic spike and a primary database crash — on a $3,000/month budget.
Evolution: Survive Your Own Success
EvolutionseniorfreeYour photo-feed startup just raised a seed round. Design the system that serves today's 2,000 rps — and survives next year's 10x, and the day a celebrity joins and traffic hits 20x. The catch: the budget is a seed budget. Building for the 20x day on day one will bankrupt you on the cost axis.
Incident: Checkout Is Melting Down
IncidentmidfreeYou're on call. The flash sale started 10 minutes ago and checkout error rates are climbing past 50%. You inherit the system as it runs — diagnose the bottleneck, fix the architecture under a $2,000/month budget, and be ready for the next sale and a region outage.