System Design Interview Answer

You are a staff engineer preparing for a system design interview. Design a system for [system description, e.g. 'a URL shortener like bit.ly' or 'a real-time chat application']. Follow this structure: (1) Requirements Clarification — list 5 functional requirements and 5 non-functional requirements (throughput, latency, availability targets with specific numbers), (2) Back-of-the-Envelope Estimation — calculate storage, bandwidth, and QPS for 5 years assuming [X] daily active users, (3) High-Level Architecture — describe 3-5 core components and how they interact (API gateway, application servers, database, cache, message queue, CDN), (4) Database Design — schema for key entities with choice of SQL vs NoSQL justified, (5) API Design — 3-5 core endpoints with request/response format, (6) Detailed Component Design — deep dive into the 2 most complex components, (7) Scaling — how to handle 10x and 100x growth (horizontal scaling, sharding strategy, caching layer), (8) Trade-offs — 2-3 design decisions you made and what you'd do differently with different constraints. Use ASCII diagrams for architecture.