HTML Tidy Online HTML Tidy is a tool for checking and cleaning up HTML source files. It is especially useful for finding and correcting errors in deeply nested HTML, or for making grotesque code legible once more. HTML Tidy Online is a tool for checking and cleaning up HTML source files. It is especially useful for finding and correcting errors in deeply nested HTML, or for making grotesque code legible once more. hedleyhtmljonathanonlineprettyprinttidy in design & dev apps & utilwith codedevelopmenthtmlwebdesignwebstandardsby 7 users