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

SeniorPrefer not to say
May 2026

Summary

Anthropic system design round for a software engineer role, structured around reviewing an existing design doc for an inference API rather than building something from scratch. The twist caught me a bit off guard and I probably misjudged where to spend my time.

Questions Asked (2)

Q1

You're given an existing design doc for an inference API. What problems do you see with it, and how would you fix them?

System DesignTechnical Trade-offsAPI & Integrations
Author's notes

I went broad and flagged a bunch of issues across the doc, which felt thorough at the time.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the doc's goals and constraints (e.g., latency, throughput, safety, cost) to ground your critique. Then systematically evaluate the design across key dimensions like API contract, scalability, reliability, and security, proposing concrete fixes with trade-offs. Conclude by prioritizing the most impactful issues and suggesting validation steps.

Pro tip: Frame your critique as collaborative and improvement-oriented, not just fault-finding. Acknowledge what the doc does well before diving into problems, and always tie fixes back to user or business impact.

1. Clarify goals and constraints

Ask about the intended use cases, expected traffic, latency SLOs, safety requirements, and cost constraints. This ensures your critique is relevant and not based on assumptions.

2. Evaluate API contract and usability

Check if the API is intuitive, versioned, and consistent. Look for issues like lack of pagination, unclear error codes, or missing idempotency keys for retries.

3. Assess scalability and performance

Review how the design handles high load: batching, caching, rate limiting, and autoscaling. Identify bottlenecks like synchronous calls to slow services or lack of backpressure.

4. Examine reliability and fault tolerance

Look for single points of failure, retry strategies, circuit breakers, and graceful degradation. Ensure the design includes monitoring, logging, and alerting.

5. Propose prioritized fixes with trade-offs

Suggest concrete improvements, explaining the trade-offs (e.g., added complexity vs. reliability). Prioritize based on impact and effort, and recommend validation via load testing or canary deployments.

Key Points to Mention

  • API versioning and backward compatibility to avoid breaking clients
  • Rate limiting and quota management to prevent abuse and ensure fairness
  • Caching strategies (e.g., response caching, embedding caching) to reduce latency and cost
  • Observability: metrics, tracing, and logging for debugging and performance monitoring
  • Security: authentication, authorization, input validation, and data privacy
  • Cost optimization: model selection, batching, and hardware utilization

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

Q2

Walk through your approach to batch processing strategy for this inference API.

System DesignTechnical Trade-offs
Author's notes

This was clearly the crux of the whole interview and we barely touched it.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the requirements and constraints of the inference API, such as latency SLAs, throughput targets, and cost considerations. Then, outline a batch processing strategy that balances efficiency and responsiveness, covering dynamic batching, queue management, and resource allocation. Finally, discuss trade-offs and how you would measure and iterate on the strategy.

Pro tip: Emphasize the importance of adaptive batching based on real-time load and latency budgets, and mention how you would handle tail latency to maintain user experience. Show awareness of cost implications and the need for monitoring to continuously optimize batch sizes.

1. Clarify Requirements and Constraints

Ask about expected request patterns, latency SLAs, throughput goals, and cost constraints to ground your strategy in concrete numbers.

2. Design Batching Mechanism

Propose a dynamic batching system that groups incoming requests based on time windows or size thresholds, with configurable parameters.

3. Manage Queue and Scheduling

Describe how requests are queued, prioritized, and dispatched to inference workers, including handling of timeouts and retries.

4. Address Trade-offs and Edge Cases

Discuss trade-offs between latency and throughput, and how to handle spikes, failures, and varying request sizes.

5. Monitor and Iterate

Explain how you would instrument the system, track key metrics (e.g., p99 latency, batch size distribution), and adjust parameters based on feedback.

Key Points to Mention

  • Dynamic batching with adjustable time and size thresholds
  • Latency vs. throughput trade-offs and tail latency management
  • Queue management strategies (e.g., priority queues, backpressure)
  • Resource allocation and autoscaling of inference workers
  • Cost efficiency and utilization metrics
  • Monitoring and continuous optimization based on real-time data

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