Design a multi-tenant Notification System

Last updated: March 13, 2026

Quick Overview

Design a multi-tenant notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Dropbox
Software Engineering Fundamentals
Software Engineer
Dropbox
March 13, 2026
Software Engineer
Onsite
Software Engineering Fundamentals
Medium

21

6

2,969 solved


Design a multi-tenant notification system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.

Dropbox asks this during the Onsite to assess your depth in software engineering. They want to see understanding of design patterns, system architecture, and the trade-offs involved in different technical approaches.

What the Interviewer Expects
  • Apply engineering principles to a realistic design scenario
  • Discuss trade-offs between different approaches with concrete examples
  • Demonstrate understanding of testability, maintainability, and extensibility
  • Connect theoretical concepts to production engineering practices
  • Discuss how the approach scales with team and codebase size
Key Topics to Cover
Code review best practices
System observability and debugging
Design patterns (Factory, Observer, Strategy, etc.)
Concurrency and thread safety
API design and RESTful conventions
How to Approach This
  1. Apply SOLID principles. Single Responsibility makes code testable, Open/Closed makes it extensible.
  2. Choose data structures based on access patterns, not familiarity.
  3. Prefer immutable data and message passing over shared mutable state for concurrency.
  4. Design APIs with RESTful conventions, versioning, meaningful errors, and pagination from day one.
Possible Follow-up Questions
  • What are the security implications of this design?
  • How would you measure the performance of this component in production?
  • How would you document this for other engineers?
  • What testing strategy would you use for this component?
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Sample Answer
Core Principles

Start by identifying which engineering principles are most relevant: **SOLID Principles**: Single Responsibility (one reason to change), Open/Closed ...

Design Approach

**API Design**: Define clear interfaces before implementation. Use RESTful conventions for HTTP APIs. Version your APIs from the start. Return meaning...


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