Architect a high-throughput Notification Engine
Last updated: November 19, 2025
Quick Overview
Design a high-throughput notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Robinhood
November 19, 202546
8
2,781 solved
Design a high-throughput notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This fundamentals question from Robinhood's System Design Round tests whether you can reason about software design at a deep level. The interviewer expects discussion of maintainability, testability, and operational considerations.
What the Interviewer Expects
- Design a complex system component applying multiple engineering principles
- Reason about system-level trade-offs: performance, reliability, developer experience
- Discuss advanced patterns: event sourcing, CQRS, distributed transactions
- Address cross-cutting concerns: observability, security, backward compatibility
- Demonstrate depth in both theoretical foundations and practical implementation
Key Topics to Cover
How to Approach This
- Apply SOLID principles. Single Responsibility makes code testable, Open/Closed makes it extensible.
- Choose data structures based on access patterns, not familiarity.
- Prefer immutable data and message passing over shared mutable state for concurrency.
- Design APIs with RESTful conventions, versioning, meaningful errors, and pagination from day one.
Possible Follow-up Questions
- How would this design change if the team size doubled?
- What testing strategy would you use for this component?
- How would you document this for other engineers?
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Core Design Principles
In designing a high-throughput notification engine for Robinhood, we will apply the CAP Theorem, which states that we can only achieve two of the following three guarantees: Consistency, Availabil...
Architecture
The architecture can be built using a Microservices approach that includes the following components: 1) A Notification Service, which handles the logic for sending notifications; 2) **An Event...
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