Design a URL Shortening for Booking.com
Last updated: September 10, 2025
Quick Overview
Design a multi-tenant url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Booking.com
System Design
Software Engineer
Booking.com
September 10, 2025Software Engineer
Onsite
System Design
Easy
26
14
4,224 solved
Design a multi-tenant url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Booking.com asks this during the Onsite to assess your architectural thinking. They want to see how you decompose a complex problem, choose appropriate technologies, and reason about failure modes. Strong candidates proactively discuss monitoring, alerting, and operational concerns.
What the Interviewer Expects
- Clearly define functional and non-functional requirements
- Propose a reasonable high-level architecture with core components
- Choose appropriate data storage solutions with basic justification
- Discuss basic scaling strategies (horizontal scaling, caching)
- Identify potential bottlenecks and suggest simple solutions
Key Topics to Cover
Database selection and data modeling
Consistency models and replication
Requirements gathering and capacity estimation
API design and rate limiting
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
- How would you handle a region-wide outage?
- How would you optimize costs as the system scales?
- How would you migrate from a monolithic to a microservices architecture?
- What monitoring and alerting would you set up on day one?
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Requirements
Functional Requirements:
- URL Shortening: The system must generate a short, unique URL for a given long URL.
- Redirection: Users should be able to access the original long URL by acces...
Capacity Estimation
Back-of-Envelope Calculations:
- Daily Requests: Assume Booking.com handles around 10 million visitors daily, with each user generating 2 URL shortens on average.
- Total Short URLs: 10 mi...
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