System Design Interview: URL Shortener

System design interviews are less about finding the "right" answer and more about showing your ability to navigate trade-offs. This prompt helps you practice that high-level thinking.

The Core Prompt

Walk me through the system design for a URL shortener like Bitly. Discuss the API design, database schema, handling high read/write volume, and how to implement a custom alias feature.

Technical Depth

This prompt covers the full stack—from how the data is stored to how it scales—providing a comprehensive review for any backend engineer.

Usage Tips

• The "Challenge" Mode: Tell the AI: "Halfway through your explanation, introduce a failure scenario (like the database going down) and ask me how I would fix it."
• Scale: Specify the load: "Design it to handle 10,000 requests per second."

Example AI Output

The AI might suggest using a NoSQL database like Cassandra for high write throughput and a Redis cache to handle the heavy read load of popular shortened URLs.