Designing a News Feed

A news feed looks simple from the outside, but building one that works for millions of users requires careful system design.

In this lesson, we'll explore how a scalable news feed can be designed using caching, databases, queues, and fanout strategies.

What Are We Building?

Imagine a social platform where users can:

• Follow other users
• Create posts
• Like posts
• Comment on posts
• View a personalized feed

The system should return the latest relevant posts quickly, even when millions of users are online.

Key idea: The feed should feel instant to the user, even if the system is doing a lot of work behind the scenes.

High-Level Architecture

A typical request might look like this:

Client
  |
  v
API Gateway
  |
  v
Feed Service
  |
  +------> Redis Cache
  |
  +------> PostgreSQL
  |
  +------> Kafka