YOUR BRIEF
What to work through
Work through the Facebook news feed as a spoken system design interview. Start by clarifying the scope, sketch a working design and explain the trade-offs behind your choices.
- Create a post
- Follow other users
- See a feed of posts from followed users, newest first
- Page back through the feed
BEFORE YOU START
Constraints to discuss
- Availability over consistency: a post may take up to 1 minute to appear
- Posting and reading the feed answer in under 500 ms
- Supports 2 billion users
- No cap on how many people a user follows or how many follow them
Need a starting point?
Watch for these common gaps as you prepare:
- Getting lost in scaling details before the basic design works
- Writing a celebrity post to millions of feeds from one host
- Ignoring hot keys in the post cache
- Offset pagination on a feed that changes while the user scrolls
Why this question is in the collection
These sources connect the problem to company interview reports or preparation guides. They do not guarantee what a company will ask you.