Mock Interviewer

Ask Coach

Clarify requirements before you design — kept separate from your stage notes.

Tap a question to start, or type your own below.

Facebook Feed System Design

Visual Problem Diagram

Scenario

Your friend posted ten minutes ago but your feed still looks like yesterday— fan-out lag or a slow ranker is the product failure, not a missing database box. Hybrid fan-out, a celebrity policy, and honest degradation when ranking times out are what interviewers grade on a Facebook-style home feed.

Design the home feed for a large social network: posts from followed accounts, ranked or chronological, paginated, and fast to scroll. The interview targets unbounded work per swipe and celebrity fan-out—not entity diagrams alone.

Constraints

Constraints will be defined in the Requirements stage.

Stages ahead

1Requirement Analysis

2API Design

3High-Level Design

4HLD Extensions

5Trade-offs

Log in to start practicing

Preview the problem below. Sign in to start your timed session, save progress, and use the AI coach.