By default, diagrams.net saves your diagrams as an XML file with the .drawio file extension. To save your diagram instead with the .xml file extension and the initial XML version tag (<?xml version="1.0" encoding="UTF-8"?>), you need to export the file.

1. Select File > Export as > XML.
   
2. Change the export settings to suit your requirements, then click Export.
   • Click the Selection Only checkbox to create an XML file with just the selected elements of your diagram. This option is disabled if nothing is selected.
   • Deselect the Compressed checkbox to save an uncompressed version of the XML file. You can also use our online tool to decompress .xml and .drawio diagram files created in diagrams.net.
   • Deselect the All Pages checkbox to only export the current diagram page to the XML file.
     
3. Enter a Filename, and select the location where you want to save the exported XML file, or click Download.
   

Depending on your browser, you may be prompted to open it with a default program, or simply save the file.