Architect a event-driven URL Shortening Engine
Last updated: June 6, 2026
Quick Overview
Design a event-driven url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Vercel
June 6, 20262
13
3,674 solved
Design a event-driven url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This is a common system design question asked during Onsite at Vercel. The interviewer expects you to demonstrate your ability to design large-scale distributed systems, make well-reasoned trade-offs, and communicate your thought process clearly. Vercel values engineers who can think about scalability from day one.
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
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 do you ensure data consistency across multiple services?
- What would the deployment pipeline look like for this system?
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Requirements
Functional Requirements:
- URL Shortening: Users should be able to submit long URLs and receive short, unique URLs.
- Redirection: When a short URL is accessed, it should redirect users ...
Capacity Estimation
Back-of-Envelope Calculations:
- Daily Requests: Assume 10,000 QPS peak translates to 864 million requests per day (10,000 * 60 * 60 * 24).
- Storage Needs: If each URL mapping (long URL...
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