Pathology is a thoroughly Mac-native XPath debugger and visualizer written entirely in Cocoa. Pathology includes the innovative ability to debug your XPath queries by proceeding through them step-by-step.

Pathology includes:

• A full-featured XPath text editor with syntax highlighting, and code auto-completion.
• Several syntax highlighting themes to choose from (in Preferences).
• Check 'Debug' to slowly proceed through the XPath expression step-by-step, seeing the filtered result nodes each step of the way.
• An interactive console with click-able error messages that lead you right to the syntax or runtime errors in your XPath or source XML.
• Each Pathology window is a ".pathology" document that can be edited, saved and re-opened later.
• A query results table contains details on the selected nodes or items. Clicking on a row focuses the corresponding node in the source XML text.
• Query result nodes are also highlighted conspicuously in the source XML text.
• Pathology's XPath engine is powered by Panthro, an open-source implementation of XPath written in Objective-C that includes the ability to debug the evaluation of an XPath expression step-by-step.