XML Tools
n ltxml sggrep, sgcount, sgrpg
n Perl XML::Parser::PerlSAX, XML::DOM
n perlSGML dtd2html, dtddiff, dtdtree
n xmldiff, XML Notepad, XML Spy
n Java
n XP, Xerces [xml4j] (XML Parsers)
n XT, Saxon, LotusXSL, Xalan (XSLT Interpreters)