Katkat
Back

Design a post privacy/visibility system

MetaSoftware Engineer · Onsite
MediumSoftware EngineerOnsiteSystem Design

Last updated

This question evaluates a candidate's ability to design access control and visibility mechanisms for social posts, covering privacy models, efficient read-time enforcement, data modeling, caching strategies, and handling dynamic friendship and privacy updates.

Design a privacy system for social media posts (similar to Facebook post privacy).

Requirements:

  • Each post can be: Public, Friends, Friends-of-friends (optional), Only me, or Custom (allowlist/denylist/groups).
  • Enforce privacy on reads (feed and direct post URL).
  • Work efficiently with caching and high read QPS.
  • Support updates to friendships and privacy settings.

Out of scope: complex regulatory auditing.