The lxml XML toolkit for Python
Download, save and convert multiple subtitles from YouTube videos
XMLJ is a Java XML Editor and validator project.
XML editor
Fast XML parser library in C
X3D is the open-standard format for 3D graphics scenes on the Web.
EasyML serialization library, to and from XML, similar to Gson
Development toolkit for Web Services and XML data bindings for C & C++
Production space for the TEI Linguistics SIG
Web Application Server Stack for Delphi/FreePascal/Lazarus
Minimalistic address book in web browser. No server or plugin needed.
XML text markup for ancient documents
XML Schema for questionnaires and PDF questionnaire generator
eXist-db is a feature rich Open Source native XML database
Simple C++ XML processing
Simulatoralive's Java libraries and programs