Group Chat and Presence
Team chat with channels of 100,000 members — ordered message logs per channel, fan-out to online members only, read state, and presence that doesn't drown the system.
This case study is part of Pro.
Free covers the C and Python courses, the first three DSA topics, the opening system design lessons and the beginner AI lessons, all with the full coach. Pro opens the rest of the library in the FollowtheDamnCode app.