Architect a low-latency URL Shortening Engine
Last updated: March 20, 2026
Quick Overview
Design a low-latency url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Stripe
System Design
Software Engineer
Stripe
March 20, 2026Software Engineer
Technical Screen
System Design
Easy
10
7
1,317 solved
Design a low-latency url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Stripe asks this during the Technical Screen to assess your understanding of the full ML lifecycle. They want to see how you translate a business problem into an ML objective, design the feature pipeline, and plan for model monitoring and retraining.
What the Interviewer Expects
- Map the business problem to a concrete ML objective
- Propose reasonable features and a baseline model
- Discuss basic model evaluation metrics
- Outline a simple serving architecture
Key Topics to Cover
Feedback loops and model retraining
Online vs offline evaluation
Model selection and architecture
Data collection and labeling strategy
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 run A/B tests on different model versions?
- How would you ensure fairness and reduce bias in the model?
- How would you handle a 10x increase in prediction requests?
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Requirements
Functional Requirements
- URL Shortening: Generate a unique short URL for each long URL input.
- Redirection: Redirect users from the short URL to the original long URL with minimal latenc...
Capacity Estimation
Back-of-Envelope Calculations
- User Base: Assume Stripe has 10 million active users.
- Requests: If each user creates 1 URL per month, that’s approximately 10 million requests per month, ...
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