XML Copy Editor!

Notepad++ is a free source code editor and Notepad replacement that supports several languages.

SynWrite is a free source code editor and notepad replacement for Microsoft Windows Operating Systems.

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.

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.

FoldingText is the markdown text editor with productivity features. Unlike other editors, FoldingText does outlining, todo lists, 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.

XML Notepad provides a simple intuitive user interface for browsing and editing XML documents.

Firstobject's free XML editor for Windows is called foxe.

XMLPad is a XML editor, XML-Schema editor, validator and a lot more:-- Full XML Schema support.-- Project system with CVS support.-- XML Schema editor with color syntax highlighting, line numbers, element range navigation, and context-dependent source assistant wizard.-- Preview and printing XML Schema in graphical diagram window. The diagram is synchronized with XML Schema editor.-- XML Schema documentation generation (ws3p.xsl) with diagram images.-- XML Schema validation and XML files validation against the underlying XML Schemas.-- Generation of XML samples from XML schema or a sample of XML Schema from XML file. Converting XSD to DTD and DTD to XSD.-- Regular expression builder and enumeration builder.-- Schema-aware XSLT editor and debugger with Active script support.-- Support for JAXB and Castor binding.-- HTML & DBF import. »

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

BaseX is a very light-weight, high-performance and scalable XML Database engine and XPath/XQuery Processor with Full Text and Update extensions.

XML Tree is a basic cross-platform tree view XML editor. It displays XML files as tree views and allows basic operations: adding, editting and deleting text nodes and their attributes. The main goal is providing a simple tool to create/edit XML configuration files for users without knowledge of XML.

EditiX is a powerful and easy to use XML editor, Visual Schema Editor, XQuery Editor and XSLT debugger for Windows, Linux and Mac OS X designed to help web authors and application programmers take advantage of the latest XML and XML-related technologies such as XSLT / FO, DocBook and XSD Schema. EditiX XML Editor now comes in two editions. EditiX Free XMLEditor Lite is free for non-commercial environments and can be downloaded without registration.

The simple yet actually fast source-level XML Editor XML Marker uses a combination of syntax-highlighting editor, tree view, and table views to help you get better insights of your XML code.

Makes working with XML as fast and convenient as never before. XML ValidatorBuddy is your XML and JSON editor to edit, validate, transform and manage even a large number of XML documents. The unique File Explorer with XML related enhancements enables everyone to work with XML in a convenient and efficient way.