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, 2026
Software 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
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. 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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Sample Answer
Requirements Clarification

Before diving into the architecture, clarify the scope with the interviewer. For Rate Limiting Service, key functional requirements include: what are ...

Capacity Estimation

Estimate the scale to drive design decisions. Assume 100M DAU with an average of 10 actions per user per day = 1B requests/day ~ 12K QPS average, ~36K...


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