Y Combinator Question 40: What Is the Spec for the Product/Feature We Want to Build?

This Y Combinator question focuses on understanding the specific details and requirements of a product or feature your startup plans to develop. Y Combinator Question 40: What Is the Spec for the Product/Feature We Want to Build?


Providing a clear and thorough specification (spec) is crucial as it outlines the intended functionalities, design, and user interactions, serving as a blueprint for development and testing.

1. Why Y Combinator Asks This Question

Y Combinator seeks to assess how well your team can define and articulate detailed specifications for new developments. A well-documented spec is indicative of a startup’s ability to plan meticulously and manage product development efficiently.

This question also helps investors gauge your team’s technical understanding and commitment to delivering products that meet specific market or user needs.

2. How to Answer the Question

When answering, provide a detailed breakdown of the product or feature’s specifications. The breakdown should include the functional requirements, user interface design, performance criteria, security features, and any integrations with existing systems.

Explain how these specifications were determined (e.g., based on market research, user feedback, and competitive analysis) and the expected impact of the product or feature on your business or users.

3. How NOT to Answer the Question

Avoid vague or incomplete descriptions that fail to provide a clear picture of what you’re planning to build.

Do not use jargon-heavy content that might obfuscate important details. It’s crucial to communicate the specifications in a way that is both comprehensive and understandable to stakeholders who may not have technical expertise.

4. An Example, Based on a Tech Startup

Let’s consider a tech startup, HomeSafe, that is developing a new feature for its smart home security app, specifically an AI-driven suspicious activity detector. Here’s how they might respond:

Product/Feature Specification:
  • Functional Requirements: “The feature will automatically analyze video feeds from home security cameras using AI to detect unusual activity. When suspicious activity is identified, the system will send real-time alerts to the homeowner’s smartphone and log the incident in the app’s activity history.”
  • User Interface Design: “The feature will be accessible via a new ‘Security Alerts’ tab in the app, which will provide a thumbnail video clip of the detected activity, details about the time and type of activity, and options for the user to dismiss the alert or contact local authorities directly from the app.”
  • Performance Criteria: “The AI algorithm should correctly identify suspicious activities with at least 95% accuracy and send alerts within 10 seconds of activity detection.”
  • Security Features: “All video data will be encrypted in transit and at rest, and the AI will run locally on the device to maintain user privacy.”
  • Integrations: “This feature will be integrated with existing smart home devices compatible with our system, including doorbell cameras and indoor/outdoor security cameras.”
  • Specification Justification: “These specifications were developed based on feedback from current users who requested faster, more reliable notifications of potential security threats, as well as an ability to interact with alerts directly through the app.
    Market analysis also indicated a strong user preference for privacy-focused security solutions, which led to our decision to run AI processing locally on user devices.”
Y Combinator evaluates how startups articulate detailed specifications for product development, assessing their capacity to meticulously plan and communicate the intended functionalities, designs, and user interactions that serve as a blueprint for execution.

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