How would you design chess.com?

To design chess.com, I'd focus on a scalable and real-time architecture. A load balancer would distribute traffic across multiple API servers. A publish-subscribe system would handle real-time events like game updates and user status. A dedicated game engine service would manage game logic. For data persistence, a write-through cache combined with a NoSQL database would ensure low latency and high availability. HTTP long polling or WebSockets would be used for efficient, real-time user status updates.