Design TikTok's For You Recommendations

1. Problem Statement

2. Architecture Discussion Map

Use this as one discussion aid, not a single correct answer. Your design should follow from the requirements, scale, and trade-offs you establish.

graph LR
    A["Design TikTok's For You Recommendations"]
    A --> F1["Real-time Analytics Clickstream, Watch time"]
    A --> F2["ML Pipeline Candidate Generation -> Ranking -> Re-ranking"]
    A --> F3["Cold Start Problem"]
    A --> F4["Latency Feed must be instant"]
    A --> F5["Content Delivery Pre-fetching"]

3. Key Focus Areas

• 1
  Real-time Analytics (Clickstream, Watch time)
• 2
  ML Pipeline (Candidate Generation -> Ranking -> Re-ranking)
• 3
  Cold Start Problem
• 4
  Latency (Feed must be instant)
• 5
  Content Delivery (Pre-fetching)

4. What the Interviewer Looks For

The interviewer probes these areas, and the report grades the interview against them.

• Objectives, scope, and estimation
• Retrieval and ranking funnel
• Real-time signals and feature infrastructure
• Model training and rollout
• Cold start, exploration, and integrity
• Serving reliability and client delivery