XMLJ is a Java XML Editor and validator project.
EasyML serialization library, to and from XML, similar to Gson
X3D is the open-standard format for 3D graphics scenes on the Web.
Relational database replication tool based on XML Schema
eXist-db is a feature rich Open Source native XML database
Java based XSLT Processor extension for syntax highlighting
XML Application Framework based on JAVA
NO LONGER MAINTAINED
EXI implementations in Java and C#
Simple tool for converting large XML-files to JSON or JSON to XML
Create XML and JSON data services from any data source
CSV to XML converter
XMLUnit provides assertions that help testing code that produces XML.