Design Challenges

Design 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.

Your 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.

You'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.