Design Recommendation Infrastructure for mobile apps
Last updated: October 6, 2025
Quick Overview
Design a scalable recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
JPMorgan
System Design
Software Engineer
JPMorgan
October 6, 2025Software Engineer
Technical Screen
System Design
Hard
34
4
4,052 solved
Design a scalable recommendation system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
JPMorgan asks this during the Technical Screen 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
- Drive the design discussion proactively with minimal interviewer guidance
- Perform detailed capacity estimation and use it to inform design decisions
- Design for global scale with multi-region deployment and data consistency
- Deep dive into 2-3 critical components with implementation-level detail
- Address complex trade-offs: CAP theorem, eventual consistency, conflict resolution
- Discuss operational excellence: deployment strategy, chaos engineering, SLOs/SLIs
- Propose a phased rollout plan from MVP to full-scale system
Key Topics to Cover
Partitioning and sharding strategies
Database selection and data modeling
High-level architecture and component design
Caching strategies (local, distributed, CDN)
Requirements gathering and capacity estimation
Monitoring, logging, and alerting
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?
- What happens if one of your database nodes goes down?
- What would the deployment pipeline look like for this system?
- How would you migrate from a monolithic to a microservices architecture?
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Requirements
Functional Requirements
- User Profile Management: Ability to create and update user profiles including preferences, transaction history, and interactions.
- Recommendation Engine: Gener...
Capacity Estimation
Back-of-Envelope Calculations
- User Base: Assume 10 million active users.
- Requests: Each user generates an average of 5 recommendation requests per day, leading to 50 million requests...
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