Design a URL Shortener System Design Interview

1. Problem Statement

2. Architecture Discussion Map

Use this as one discussion aid, not a single correct answer. Your design should follow from the requirements, scale, and trade-offs you establish.

graph LR
    A["Design a URL Shortener"]
    A --> F1["Unique ID Generation Base62 vs UUID vs Counter"]
    A --> F2["Collision Handling Hash checks"]
    A --> F3["Read Optimization Caching Hot Redirects"]
    A --> F4["Database Choice SQL vs NoSQL for Mappings"]
    A --> F5["Analytics Pipeline Separation of concerns"]

3. Key Focus Areas

• 1
  Unique ID Generation (Base62 vs UUID vs Counter)
• 2
  Collision Handling (Hash checks)
• 3
  Read Optimization (Caching Hot Redirects)
• 4
  Database Choice (SQL vs NoSQL for Mappings)
• 5
  Analytics Pipeline (Separation of concerns)

4. What Strong Candidates Should Demonstrate

• ✓Translate product scope into measurable redirect and creation SLOs.
• ✓Use capacity estimates to justify key length, storage, cache, and partitioning decisions.
• ✓Separate the latency-critical redirect path from asynchronous analytics.