Design a Rate Limiting Service
Last updated: June 10, 2026
Quick Overview
Design a geo-distributed rate limiting system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
Goldman Sachs
System Design
Software Engineer
Goldman Sachs
June 10, 2026Software Engineer
Onsite
System Design
Medium
290
5
2,964 solved
Design a geo-distributed rate limiting system that handles millions of requests. Discuss trade-offs in consistency, availability, and performance.
System design interviews at Goldman Sachs typically last 45-60 minutes. You are expected to drive the conversation, starting from requirements gathering through to a detailed architecture. The interviewer will evaluate your ability to handle ambiguity and make practical engineering decisions.
What the Interviewer Expects
- Systematically gather requirements and estimate capacity (QPS, storage, bandwidth)
- Design a scalable architecture with clear component responsibilities
- Make well-reasoned database and caching decisions with trade-off analysis
- Address consistency vs availability trade-offs specific to the use case
- Discuss partitioning strategy, replication, and data modeling
- Cover failure handling, monitoring, and alerting strategies
Key Topics to Cover
Message queues and async processing
Security and authentication
Requirements gathering and capacity estimation
High-level architecture and component design
Load balancing and horizontal scaling
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
- What monitoring and alerting would you set up on day one?
- How would you handle a region-wide outage?
- How would you implement rate limiting to protect the system?
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Requirements
Functional Requirements
- Request Tracking: The system must track requests per user and per IP address to enforce rate limits.
- Geographic Distribution: The rate limiting service should...
Capacity Estimation
Back-of-Envelope Calculations
- User Base: Assume Goldman Sachs has 100,000 active users.
- Average Requests/User: Assume each user makes an average of 50 requests per minute.
- **Total...
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