Currently telecommunication technology has developed in Indonesia, one of the communication technologies that is very rapidly developing at this time is android-based telecommunications technology. Android is one of the operating systems for mobile devices based on Linux, developed by Google with other companies incorporated into the open handset alliance. Android provides an open platform for developers to create their own applications that can be used by a variety of mobile devices. Utilization of telecommunications technology that is increasingly developing allows one to communicate more easily and practically one of them is by chatting application. Chatting is an instant message in computer network technology to send information to other users connected via an internet connection. From this problem, this study aims to develop an chat application based on Android ChatYuk !. In the implementation phase, from the side of the application that will be built using the Java programming language and TypeScript. The tools used are Software Development Kit (SDK), IDE (Integrated Development Environment), and Node.js with the text editor used is Android Studio and Visual Code. And use Firebase as Backend as a Service (BaaS) and also as a database. To test the user uses an Android Virtual Device (AVD) and an Android-based smartphone