System design is the art of architecting scalable, reliable, and maintainable systems. This module applies Node.js knowledge to real-world system design problems — covering the architectures behind URL shorteners, chat systems, rate limiters, task management platforms, and e-commerce backends.

Each section walks through requirements, API design, data modeling, scaling strategies, and trade-offs — preparing you for both building production systems and acing system design interviews.

Knowing Node.js APIs isn’t enough — you need to know how to compose them into real systems. System design bridges the gap between “I can write an Express route” and “I can design a system that handles 10M users.”

flowchart LR
    URL["7.1 URL Shortener"] --> Chat["7.2 Chat System"]
    Chat --> Rate["7.3 Rate Limiter"]
    Rate --> Task["7.4 Task Management"]
    Task --> Ecom["7.5 E-Commerce Backend"]

    style URL fill:#4f46e5,color:#fff
    style Chat fill:#7c3aed,color:#fff
    style Rate fill:#059669,color:#fff
    style Task fill:#d97706,color:#fff
    style Ecom fill:#dc2626,color:#fff