This is a small application I've built to transform unreadable, ugly XML into nice, clean, pretty, human readable XML. It is written in C# on top of the .NET framework (3.5). The software can handle multiple documents at a time (I managed to get it up to 180+ documents before giving up) and each file is syntax highlighted. All the software does is try to reformat your XML to indent your code and warn you of any structural issues with the document.
2017 Luke Browning