XMLmind XML Editor!

Altova XMLSpy is the industry's best-selling XML editor and development environment for modeling, editing, transforming, and debugging XML-related technologies. It offers the world’s leading graphical schema designer, a code generator, file converters, debuggers, profilers, full database integration, support for XSLT, XPath, XQuery, WSDL, SOAP, XBRL, and Office Open XML (OOXML) documents, plus Visual Studio and Eclipse plug-ins, and more.

<oXygen/> XML Editor is a cross platform XML Editor providing tools for XML authoring, XML conversion, XSL, XSLT, XQuery, XML Schema, DTD, Relax NG and Schematron development, SOAP and WSDL.

TreeLine just stores almost any kind of information. A tree structure makes it easy to keep things organized. And each node in the tree can contain several fields, forming a mini-database. The output format for each node can be defined, and the output can be shown on the screen, printed, or exported to html. TreeLine can also act as a basic editor for any kind of XML file.

The Exchanger XML Editor is a Java-based product that provides unique functionality for viewing, authoring and editing XML data and documents. Last version was opensourced in 2010: https://code.google.com/archive/p/exchangerxml/downloads

Guide to learn programming

ExamXML displays XML documents in a tree view, highlighting differences down to the level of elements, words or attributes, so that you can view exactly which attributes and elements have been added, modified or deleted. Red color means that the element has been removed, green means that the element has been changed.