Design a URL Shortening Service
Last updated: October 15, 2025
Quick Overview
Design a low-latency url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Amazon
October 15, 202574
5
3,188 solved
Design a low-latency url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This fundamentals question from Amazon's System Design Round tests whether you can reason about software design at a deep level. The interviewer expects discussion of maintainability, testability, and operational considerations.
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 this design change if the team size doubled?
- How would you measure the performance of this component in production?
- What testing strategy would you use for this component?
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Core Design Principles
For designing a URL shortening service, we will apply the Single Responsibility Principle to ensure that each component of the system has a clear purpose, such as URL storage, retrieval, and analy...
Architecture
The architecture will consist of a microservices approach with the following components: a REST API for client interactions, a Database for storing URL mappings, and a Cache Layer (e.g., R...
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