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

SeniorPrefer not to say
May 2026

Summary

Got a system design question for what seemed like a senior engineering or TPM role at Google. The problem was framed around eBay but I'm pretty sure it was just a proxy for how Google handles policy enforcement at scale. One question, no warmup.

Questions Asked (1)

Q1

Design a system that automatically filters out restricted or prohibited product listings on a large e-commerce marketplace.

System DesignTechnical Trade-offsProduct Strategy
Author's notes

I jumped straight into a classifier pipeline and the interviewer kind of just waited.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scale, then propose a multi-layered system combining rule-based filters, ML classifiers, and human review. Emphasize trade-offs between precision, recall, latency, and cost, and describe how to handle evolving policies and adversarial sellers.

Pro tip: Frame the problem as a precision-recall trade-off: false negatives (bad listings live) harm trust and may be illegal, while false positives (good listings blocked) hurt sellers and revenue. Propose a tiered enforcement strategy with appeals and feedback loops to continuously improve.

1. Clarify Requirements and Scale

Ask about listing volume, types of restricted items, latency needs, and integration points. Define success metrics like precision, recall, and time-to-takedown.

2. Design Multi-Layer Detection Pipeline

Propose a pipeline: rule-based filters (keywords, image hashes), ML models (text, image, multimodal), and anomaly detection. Include a human review queue for ambiguous cases.

3. Address Data and Model Lifecycle

Discuss training data sourcing, labeling, and handling class imbalance. Cover model retraining, drift detection, and adaptation to new restricted categories.

4. Define Enforcement and Feedback Loops

Specify actions: auto-block, flag for review, or allow with monitoring. Include seller appeals, user reporting, and using feedback to improve models.

5. Discuss Trade-offs and Scalability

Analyze trade-offs between precision/recall, latency, cost, and seller experience. Describe how to scale horizontally and handle peak loads.

Key Points to Mention

  • Precision vs. recall trade-off and its business impact
  • Multi-modal detection (text, image, metadata) and ensemble methods
  • Human-in-the-loop review for edge cases and appeals
  • Adversarial adaptation (sellers obfuscating keywords/images)
  • Feedback loops from user reports and seller appeals
  • Scalability and low-latency inference at marketplace scale

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