Since its inception in 1984, TRON Project has been working to realize an environment where many objects surrounding us are embedded with computers, and operate in a cooperative and organic manner. This concept is partially being realized now under the name of the Internet of Things (IoT) or ubiquitous computing. Our next step is to develop an environment where API implemented in many types of devices and systems can be interconnected and integrated with each other across manufactures and device types. Open API SWG has been established under IoT Working Group (WG) of TRON Forum to discuss the specifications and technologies that are needed to achieve our next goal.