- Responsible for the development of core modules in the IM backend, including but not limited to: one-on-one chat / group chat, message synchronization, historical messages, offline messages, acknowledgment mechanisms, editing historical messages, and read/unread status.

- Design and develop backend services for the instant messaging system, including message delivery, session management, message storage, offline messages, file management, and push notifications.

- Optimize the stability and real-time performance of message channels (such as WebSocket, MQTT, etc.) under different network environments.

- Responsible for core logic including user status management, message deduplication and idempotency, message acknowledgment, and read status synchronization.

- Collaborate with the client team to define interface protocols and data structures (such as ProtoBuf, JSON, MsgPack, etc.).

- Build a high-performance, highly available system architecture that supports millions of concurrent online users.

- Participate in the development of operational tools, log monitoring, and anomaly warning systems to enhance overall system stability.