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Openai·Software Engineer·Onsite - System Design / Architecture·Senior

Senior
May 2026

Summary

Interviewed for a software engineering role at OpenAI and got a system design question to design ChatGPT itself. Kind of surreal being asked to design the product you're interviewing to work on.

Questions Asked (1)

Q1

Design ChatGPT. Walk through the architecture of a large-scale conversational AI product from scratch.

System DesignTechnical Trade-offsAPI & Integrations
Author's notes

This one is deceptively massive.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scope, then propose a high-level architecture that covers the end-to-end flow from user input to response generation. Focus on scalability, low latency, and safety, and be prepared to dive deep into specific components like model serving, caching, and rate limiting.

Pro tip: Emphasize trade-offs between latency, cost, and quality, and discuss how you would monitor and iterate on the system using A/B testing and user feedback.

1. Clarify Requirements

Ask questions to understand expected scale (e.g., users, QPS), latency requirements, safety and compliance needs, and budget constraints.

2. High-Level Architecture

Sketch the main components: client, API gateway, load balancer, inference service, model servers, cache, database, and monitoring. Explain how they interact.

3. Deep Dive into Critical Components

Discuss model serving (e.g., GPU/TPU clusters, batching, quantization), caching strategies (e.g., semantic caching), and rate limiting/authentication.

4. Scalability and Reliability

Explain how to scale horizontally, handle failures (e.g., retries, circuit breakers), and ensure high availability across regions.

5. Safety and Monitoring

Describe content moderation, abuse detection, logging, and metrics for performance and quality, and how to iterate using feedback.

Key Points to Mention

  • Model serving infrastructure with GPU/TPU clusters and dynamic batching
  • Caching strategies to reduce latency and cost (e.g., semantic caching, KV cache)
  • Rate limiting, authentication, and API gateway design
  • Content moderation and safety filters (e.g., OpenAI's moderation API)
  • Monitoring, logging, and A/B testing for continuous improvement
  • Trade-offs between latency, cost, and response quality

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.