XUL Explorer is a lightweight XUL IDE, built as a XULRunner application that provides an easy way to experiment with XUL. It's a simple editor that can preview XUL inline or in a separate popup window. It has a list of code snippets (small fragments of XUL or JavaScript) that can be quickly inserted into the editor. The XUL can be load and saved to files. A XUL validator and the JavaScript Error Console is available to help debug problems.