Altova XMLSpy - The XMLSpy XML Editor is a powerful tool for editing XML and related technologies. It is the only XML Editor with patented SmartFix validation, enterprise-grade editors, converters, debuggers, and code generators.

MarkLogic - Schema-agnostic Enterprise NoSQL database technology, coupled w/ powerful search & flexible application services

XML Copy Editor - XML Copy Editor is a fast, free, validating XML editor.

BaseX - BaseX is a very light-weight, high-performance and scalable XML Database engine and XPath/XQuery...

Oxygen XML Editor - Oxygen XML Editor provides a comprehensive suite of XML authoring and development tools.

Apache Anakia - XML Databases