CasperJS is an open source functional testing utility written in JavaScript that allows testing and navigation of web pages using a headless WebKit browser. It provides a high level API to programmatically browse pages, fill forms, click links, and assert page content. CasperJS can be used to write automated functional tests to test the integration of different layers of an application from routing to views by testing business rules and page integration. For example, a CasperJS test script is shown that navigates to a site, clicks a link, asserts URL and page content, and verifies specific text is found on the page.