Design a A/B Testing for Uber
Last updated: February 18, 2026
Quick Overview
Design a real-time a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Uber
System Design
Software Engineer
Uber
February 18, 2026Software Engineer
Onsite
System Design
Medium
125
12
4,816 solved
Design a real-time a/b testing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Uber 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
- 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
Monitoring, logging, and alerting
Load balancing and horizontal scaling
Consistency models and replication
Failure handling and fault tolerance
Security and authentication
Partitioning and sharding strategies
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 would the deployment pipeline look like for this system?
- How would you implement rate limiting to protect the system?
- How would you optimize costs as the system scales?
- How would you handle schema migrations with zero downtime?
Practice a Similar Problem on Codemia
Solve a related problem with our interactive workspace, get AI feedback, and view detailed solutions.
Solve on CodemiaSample Answer
Requirements
- Functional Requirements:
- Ability to create, manage, and run A/B tests across different features of the Uber app.
- Real-time metrics collection and analysis for each variant of the A/B tes...
Capacity Estimation
- Estimate QPS:
- Assume Uber has approximately 100 million users.
- If we assume 10% of users are active at peak times, that’s about 10 million active users.
- If each user generates 3 A/B ...
Submit Your Answer
Markdown supported