The Internet of Things (IoT) aims at sensing and altering our surrounding environment through connected objects to improve everyday life. IoT applications are built using interconnected objects with a goal to provide added-value services. However, there are still challenges in providing a secure, robust and easy-to-use end-user platform for development of such applications. In this paper, we present a end-user tool for supporting the design and deployment of smart home IoT applications. The tool first provides a graphical user interface to specify an IoT application using a rule-based composition language. Automated analysis techniques can then be called for verifying that the designed application is correct (e.g., free of deadlocks). Finally, the tool provides a rule execution engine to support application deployment. The tool is built by implementing a set of components on top of Mozilla WebThings platform, which is a concrete implementation of W3C's Web of Things specification.