What is XML Viewer - Reader and Opener?

It's a free tool for reading XML documents. You can use it to open the said files saved to your device, so you don't need to have them anywhere else. It is not an app that will run your device more intensively. It's a handy utility. It only takes a single click, and it will instantly open the file. Additionally, the app allows you to convert XML files into PDFs.

And if you still have problems, you can contact the developer with a support form.