Design TikTok (For You Feed)
Hard · System Design · about 45 minutes
Asked at ByteDance, Meta, Snap, Pinterest, Netflix.
Design TikTok's For You feed for ~1B daily users: an endless stream of short videos chosen for each user by a recommendation system rather than by who they follow. The next video must start within 200ms of a swipe, a batch of recommendations must come back within 200ms, ~50M new videos arrive per day, and the feed should adapt within the same session to what the user just watched.