Briefly describe the purpose and core functionality of a URL shortening service like Bitly.

Design the RESTful API endpoint(s) for creating short URLs. Specify HTTP methods, request parameters (e.g., long URL, custom alias, expiration date), and expected JSON response format.

Discuss error handling strategies for the URL shortening API requests, including common error types and their corresponding HTTP status codes and response formats.

Describe different approaches for generating a unique short code (hash) for a URL shortening service, such as base62 encoding of an incrementing ID or random string generation. Discuss their trade-offs.

Explain how to ensure the generated short code is unique and handle potential collisions, especially for random string generation.

Propose a relational database schema (e.g., for PostgreSQL) to store the mapping between short URLs and long URLs. Include essential fields and their data types.

Discuss indexing strategies for efficient lookup of short codes in the database. Briefly mention considerations for choosing between SQL and NoSQL databases for this service.

Explain the end-to-end flow from when a user clicks a short link to being redirected to the original long URL.

Specify the HTTP status codes used for redirection (e.g., 301, 302, 307, 308) and explain when each is appropriate, along with their implications for SEO and caching.

Provide a high-level conceptual overview of the system components (e.g., API Gateway, Load Balancer, Web Servers, Database, Cache, Message Queue) for a URL shortening service and describe how they interact.

Discuss how the design addresses scalability for both read (redirects) and write (short URL creation) operations.

Address single points of failure and strategies for high availability (e.g., replication, sharding, caching) in the URL shortening service.

Briefly touch upon analytics and how click data could be captured and processed in a URL shortening service.