System Design Interview Question: Design URL Shortener

Designing a URL shortener tool requires considering functional and non-functional requirements, estimating the number of unique URLs needed, and implementing key components like users, load balancer, web servers, URL shortener service, and database. The API design includes creating a short URL and redirecting to the long URL. The database should be optimized for fast read and write operations, and the URL shortener service can use methods like hashing, auto-increment IDs, or custom algorithms. Caching and database scaling strategies are important for high availability and low latency. Security considerations include input validation, rate limiting, monitoring and logging, obfuscation, and link expiration.