Certain aspects direct to systems and methods for defining interactions between internet of things (IoT) devices. The system includes a gateway device, which is communicatively connected to a control device and to multiple IoT devices. The gateway device provides a web user interface (UI), and a user at the control device may operate the web UI to generate a rule command defining an interaction between two IoT devices. The interaction includes an event occurred at a first IoT device, and an action performed at a second IoT device triggered by the event. Upon receiving the rule command, the gateway device creates a corresponding interaction rule. When the gateway device receives a signal from the first IoT device to indicate that the event has occurred, the gateway device generates a triggering command based on the interaction rule, and sends the triggering command to the second IoT device to trigger the action.