Treebeard is an XSLT IDE that allows you to load an XML file and an XSLT file (from the Web or from the local file system), edit either file, and then perform transformations. Some features include syntax highlighting, a pluggable XSLT transformer, a template browser, SAX transformations (so you can transform large files - 4MB tested), regular expression find, and displaying transformation results in HTML or plain text.