XMLSpy Enterprise Edition 

Altova XMLSpy 2006 Enterprise Edition is the industry standard XML development environment for modeling, editing, debugging and transforming all XML-related technologies, then automatically generating runtime code in multiple programming languages.
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Stylus Studio XML Enterprise Edition 

Stylus Studio XML IDE features XML Editing, Debugging, Testing/Benchmarking & Deployment Tools for any XML technology, including XML Schema, DTD, XSL/XSLT, XPath, XQuery, XML Mapping, Web Services, SQL/XML, EDI, Legacy Data Integration and more.
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XMLwriter XML Editor 

XMLwriter is a powerful XML editor for Windows designed to help web authors and web application programmers take advantage of the latest XML and XML-related technologies such as XSLT and XSD Schemas.
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Peter's XML editor 

XML editor which allows editing using a tree view or syntax highlighted source editor. The tool provides a range of feature in an intuitive easy to use environment.
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