Software internationalization is often necessary when distributing software applications to different regions around the world. In many cases, developers often do not internationalize a software application at the beginning of the development stage. To internationalize such an existing application, developers need to externalize some hard-coded constant strings to resource files, so that translators can easily translate the application to be in a local language without modifying its source code. Since not all the constant strings require externalization, locating those need-to-translate constant strings is a basic task that the developers must conduct. In this paper, we present TranStrL, an Eclipse plug-in tool that automatically locates need-to-translate constant strings in Java code. Our tool maintains a pre-collected list of API methods related to the Graphical User Interface (GUI), and then searches for need-totranslate strings in the source code starting from the invocations of these API methods using string-taint analysis.