Design a large-scale Load Balancing Platform
Last updated: June 6, 2026
Quick Overview
Design a scalable load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Instacart
June 6, 2026169
6
3,985 solved
Design a scalable load balancing system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
This fundamentals question from Instacart's Onsite 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?
- What testing strategy would you use for this component?
- How would this design change if the team size doubled?
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
Core Design Principles
For designing a scalable Load Balancing Platform at Instacart, the core design principles that apply are:
- Single Responsibility Principle (SRP): Each component of the load balancer should have...
Architecture
The architectural approach for the load balancing system consists of a microservices-based architecture:
- Load Balancing Layer: This will distribute incoming requests across multiple backend se...
Submit Your Answer
