• http://www.gnu.org/software/emacs/

  • two specialized XML modes PSGML and nXML

  • syntax highlighting

  • schema driven markup completion

  • not WYSIWYG, you work directly with markup (not suitable for “ordinary” users)

  • the most powerful editor in the world

  • it takes some time to get familiar with not so conventional UI

  • runs on almost any platform

  • free, GPL license