Abstract: A system for managing online group chat and methods for making and using same. A server computer can create a topic in a chat group and receive a request from a user device for a member of the chat group to join the topic. The request can be in response to activation of a user interface for the topic on the user device. The member can be permitted in real time to join a topic subgroup associated with the topic upon determination that a membership of the topic subgroup is less than a maximum participant number. The maximum participant number can be at least partially based on a messaging service capacity of the server. A publish-subscribe messaging service can be offered for the topic subgroup. Advantageously, the topic subgroup can be dynamically updated based on operation on the user device to reduce server workload and improve user experience.