Design A/B Testing Infrastructure for microservices

Last updated: August 29, 2025

Quick Overview

Design a low-latency a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Coinbase
System Design
Software Engineer
Coinbase
August 29, 2025
Software Engineer
System Design Round
System Design
Easy

236

3

2,694 solved


Design a low-latency a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

This is a common system design question asked during System Design Round at Coinbase. 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. Coinbase values engineers who can think about scalability from day one.

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
Consistency models and replication
High-level architecture and component design
Requirements gathering and capacity estimation
Security and authentication
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 handle a 10x increase in traffic overnight?
  • How would you handle schema migrations with zero downtime?
  • What monitoring and alerting would you set up on day one?
  • What happens if one of your database nodes goes down?
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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For A/B Testing Infrastructure for microservices, key functional requirem...

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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