The Saxon XSLT and XQuery processor, developed by Saxonica
eXist-db is a feature rich Open Source native XML database
CAM XML Editor for XML+JSON+Hibernate+SQL Open-XDX sponsored by Oracle
DocBook Publishing Made Easy
Built for enterprise level and highly customized websites
Software builder for both veteran programmer and novice.
Information Manager(split/analyze/compare/combine).
A Java implementation of XProc: An XML Pipeline Language
xslet project provides some XSL libraries and applets.
Tool for parsing, verifying, browsing and converting EDIFACT and X12
WPИ-XM is a web server stack for professional PHP development.