XMLSPY is the original Integrated Development Environment (IDE) for XML that includes all major aspects in one powerful and easy-to-use product: a validating XML editor, a Schema/DTD editor with schema validation, and an XSL editor with support for any external XSLT processor.
CAM Editor is a complex open source application to write or edit XML code and related technologies. Mainly, it has support for XML and is a WYSYWYG tool that provides preview of final document.
Is designed to write XML schema and JSON code. Includes different types of built in templates and code list values.
Can create XML code with SQL data retrieved from a database, it has support for XSLT and XPath and also allows to import data from documents.
The CAM Editor is sponsored by Oracle for more improvements and continuous development.