Design a YouTube Recommendation System

Last updated: June 17, 2026

Quick Overview

Design a recommendation engine for YouTube. Cover candidate generation, ranking models, user embedding and content features, handling cold start for new videos, and balancing engagement with content diversity.

Google
System Design
Software Engineer
Google
June 17, 2026
Software Engineer
Onsite
System Design
Hard

217

0

449 solved


Design a recommendation engine for YouTube. Cover candidate generation, ranking models, user embedding and content features, handling cold start for new videos, and balancing engagement with content diversity.

How to Approach This
  1. Start by clarifying functional and non-functional requirements with the interviewer.
  2. Estimate the scale: QPS, storage, bandwidth. This drives your design decisions.
  3. Draw a high-level architecture first, then deep dive into 1-2 critical components.
  4. Discuss trade-offs explicitly (e.g., consistency vs availability, SQL vs NoSQL).
  5. Address failure scenarios, monitoring, and how the system handles 10x traffic spikes.
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