Design a URL Shortening Service
Last updated: January 16, 2026
Quick Overview
Design a distributed url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Apple
System Design
Software Engineer
Apple
January 16, 2026Software Engineer
Onsite
System Design
Medium
179
5
4,432 solved
Design a distributed url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Apple typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
Monitoring, logging, and alerting
Database selection and data modeling
High-level architecture and component design
Caching strategies (local, distributed, CDN)
How to Approach This
- Start by clarifying functional and non-functional requirements with the interviewer.
- Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
- Draw a high-level architecture first, then deep dive into 1-2 critical components.
- Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
- Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
- What happens if one of your database nodes goes down?
- How would you implement rate limiting to protect the system?
- What monitoring and alerting would you set up on day one?
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
Requirements
- Functional Requirements:
- Users must be able to create a short URL that redirects to a long URL.
- Users should be able to retrieve the original long URL using the short URL.
- T...
Capacity Estimation
- Estimating Traffic:
- Assume 1 million users generating 10 short URLs per user per month = 10 million short URLs per month.
- Assume 100,000 requests per minute for redirection during ...
Submit Your Answer
Markdown supported