KST International Conference (KST) has been established with the aim in mind that a sustainable community will be achieved through continuous studies and share resources. It provides a central forum for experts and developers to promote, share, and discuss various issues and developments in the broad field of Computational Intelligence, Intelligent Application, Intelligent Computer Networks and Systems, and Emerging Intelligent Technologies. KST-2021 is the 13th annual International conference. It will provide an opportunity for young researchers to demonstrate their talent and interesting research ideas. The conference will benefit people who are actively involved in research related to computational intelligence and its applications in Thailand.