System Design
Interview Problems
9problems · go forth!
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easy
Design a URL Shortener
Best first problem — covers ID generation, caching, and read-heavy design in 45 min.
medium
Design a Rate Limiter
Every API needs one. Tests distributed counters, Redis atomicity, and failure modes.
hard
Design WhatsApp
The classic hard problem. Touches real-time connections, fan-out, and message ordering.
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