Instagram Feed System Design
Visual Problem Diagram
Scenario
Reels and photos share one home feed but media bytes dwarf text metadata—ranking must not block on transcoding, and a influencer post cannot fan out 50M mailbox writes. Media pipeline + hybrid feed is the Instagram-shaped interview.
Design Instagram-style home feed with photo/video posts, following graph, ranking, and optional stories. Media upload and CDN sit alongside social feed mechanics—both must be addressed.
You should support media post, feed read, explore/discovery hook, likes, and stories TTL. Be ready to explain upload pipeline and celebrity fan-out policy.
Constraints
Upload media post, following feed, explore tab, likes/comments, stories 24h, profiles
< 300 ms feed p95, media start < 2s, 99.9% availability, eventual counts OK briefly
1B users, 500M DAU, heavy CDN egress, viral posts millions of likes