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Google·Product Manager·Onsite - System Design / Architecture·Senior

Senior
May 2026

Summary

Google PM interview, one question about a login endpoint. Pretty technical for a PM role, which I wasn't fully expecting.

Questions Asked (1)

Q1

Walk me through the design of a login endpoint in detail.

System DesignAPI & IntegrationsTechnical Trade-offs
Author's notes

I started with the basics, POST request, credentials in the body, server validates against a hashed password in the DB, returns a token.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the requirements and constraints of the login endpoint, then walk through the design from a user experience and product perspective, covering authentication methods, security, scalability, and trade-offs. Emphasize how the design aligns with Google's product ecosystem and user expectations.

Pro tip: Show that you understand the balance between security and user friction, and mention how you would measure success through metrics like login success rate and time-to-login.

1. Clarify Requirements

Ask questions to understand the scope: expected scale, supported authentication methods, compliance needs, and integration with existing systems.

2. Define User Flow

Outline the step-by-step user experience from entering credentials to receiving a session token, including error handling and recovery paths.

3. Design API Contract

Specify the endpoint URL, HTTP methods, request/response formats, status codes, and versioning strategy.

4. Address Security & Scalability

Discuss security measures like rate limiting, encryption, and token management, and how the design scales horizontally.

5. Evaluate Trade-offs & Metrics

Compare design choices (e.g., OAuth vs. traditional login) and define success metrics to guide iterations.

Key Points to Mention

  • Authentication methods: password, OAuth, biometrics, and multi-factor authentication
  • Security best practices: HTTPS, hashing, salting, rate limiting, and CSRF protection
  • Token management: JWT vs. session cookies, expiration, and refresh tokens
  • Scalability considerations: load balancing, caching, and database sharding
  • User experience: minimizing friction, clear error messages, and account recovery
  • Metrics: login success rate, latency, and abandonment rate

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