Design URL Shortening Infrastructure for real-time analytics
Last updated: February 19, 2026
Quick Overview
Design a event-driven url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Citadel
February 19, 20263
7
4,015 solved
Design a event-driven url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Citadel asks this during the Onsite to assess your depth in software engineering. They want to see understanding of design patterns, system architecture, and the trade-offs involved in different technical approaches.
What the Interviewer Expects
- Apply engineering principles to a realistic design scenario
- Discuss trade-offs between different approaches with concrete examples
- Demonstrate understanding of testability, maintainability, and extensibility
- Connect theoretical concepts to production engineering practices
- Discuss how the approach scales with team and codebase size
Key Topics to Cover
How to Approach This
- Apply SOLID principles. Single Responsibility makes code testable, Open/Closed makes it extensible.
- Choose data structures based on access patterns, not familiarity.
- Prefer immutable data and message passing over shared mutable state for concurrency.
- Design APIs with RESTful conventions, versioning, meaningful errors, and pagination from day one.
Possible Follow-up Questions
- How would you document this for other engineers?
- How would you handle backward compatibility?
- How would this design change if the team size doubled?
Practice a Similar Problem on Codemia
Solve a related problem with our interactive workspace, get AI feedback, and view detailed solutions.
Solve on CodemiaSample Answer
Core Design Principles
For the URL shortening system, the core design principles include Separation of Concerns, Single Responsibility Principle, and Fail Fast. Separation of Concerns is crucial as it allows...
Architecture
The architecture for the URL shortening system at Citadel would be based on a Microservices approach, utilizing an Event-Driven architecture with a Kafka message broker to handle real-time...
Submit Your Answer
