Build a event-driven URL Shortening Pipeline

Last updated: April 19, 2026

Quick Overview

Design a event-driven url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Amazon
System Design
Software Engineer
Amazon
April 19, 2026
Software Engineer
System Design Round
System Design
Medium

7

6

3,577 solved


Design a event-driven url shortening system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

ML system design at Amazon goes beyond model selection. This System Design Round question evaluates your ability to design end-to-end ML pipelines, from data collection to model serving, while considering production constraints like latency and reliability.

What the Interviewer Expects
  • Define clear ML objectives with appropriate loss functions and metrics
  • Design a comprehensive feature engineering pipeline
  • Discuss model selection with trade-offs (complexity vs interpretability vs latency)
  • Plan online and offline evaluation strategies including A/B testing
  • Address serving infrastructure: batch vs real-time, latency requirements
  • Consider data quality, labeling strategy, and feedback loops
Key Topics to Cover
Feedback loops and model retraining
Training pipeline and infrastructure
Monitoring and model degradation detection
Online vs offline evaluation
Model selection and architecture
How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
Possible Follow-up Questions
  • How would you ensure fairness and reduce bias in the model?
  • How would you handle a 10x increase in prediction requests?
  • How would you run A/B tests on different model versions?
  • How would you debug a model that works well offline but poorly online?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For event-driven URL Shortening Pipeline, key functional requirements inc...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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