XML Copy Editor - XML Copy Editor is a fast, free, validating XML editor.
OneNote - Get the OneNote app for free on your tablet, phone, and computer, so you can capture your ideas and to-do lists in one place wherever you are. Or try OneNote with Office for free.
Oxygen XML Editor - Oxygen XML Editor provides a comprehensive suite of XML authoring and development tools.
Evernote - Bring your life's work together in one digital workspace. Evernote is the place to collect inspirational ideas, write meaningful words, and move your important projects forward.
Liquid Studio - XML Tools Provider: XML Studio - Graphical XML Schema Editor.
AllMyNotes Organizer - AllMyNotes Organizer is a multi-functional hierarchical information manager for Windows.