Can you explain how you would design a URL shortening service like Bitly? What considerations would you take into account for scalability, performance, and data integrity?

To design a URL shortening service, I would first consider a unique key generation strategy, possibly using base conversion or hash functions. For scalability, I would implement distributed databases with sharding strategies. Caching should be utilized to speed up access to frequently requested URLs. Data integrity is paramount, so I would ensure that we have proper validation and error handling for duplicate URLs.