M5 Design WeChat Steps Ranking

Social leaderboards, write amplification, and friend-scoped ranking at scale

Design a daily fitness step ranking system among friends (WeChat-style). Cover data ingestion from mobile health APIs, friend-scoped leaderboard design, on-demand vs precomputed ranking tradeoffs, write amplification analysis, Redis sorted sets for real-time ranking, midnight reset strategies, anti-cheating heuristics, and privacy controls.

Estimated time: 15 minutes

Stuck on something? The AI tutor sees this lecture—just ask.