Design a Load Balancing Service
Last updated: January 27, 2026
Quick Overview
Design a multi-tenant load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Snapchat
January 27, 202633
6
684 solved
Design a multi-tenant load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This fundamentals question from Snapchat'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
- 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
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
- What are the security implications of this design?
- How would you handle backward compatibility?
- What testing strategy would you use for this component?
- How would you measure the performance of this component in production?
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Core Design Principles
For designing a multi-tenant load balancing service at Snapchat, we need to focus on Separation of Concerns and Single Responsibility Principle. Each component of the load balancer should hand...
Architecture
The architecture of the load balancing service will consist of several key components: a Frontend Load Balancer that receives incoming requests and routes them based on predefined algorithms (e.g....
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