XML Copy Editor - XML Copy Editor is a fast, free, validating XML editor.
Notepad++ - A free source code editor which supports several programming languages running under the MS Windows environment.
Oxygen XML Editor - Oxygen XML Editor provides a comprehensive suite of XML authoring and development tools.
Atom - At GitHub, we’re building the text editor we’ve always wanted: hackable to the core, but approachable on the first day without ever touching a config file. We can’t wait to see what you build with it.
Liquid Studio - XML Tools Provider: XML Studio - Graphical XML Schema Editor.
Visual Studio Code - Build and debug modern web and cloud applications, by Microsoft