1)   AltovaXML 2007
AltovaXML is a FREE XML standards processor that includes the Altova XSLT 1.0 engine, XSLT 2.0 engine, XQuery engine, and XML validator. Now developers can use the same processors found in Altova XMLSpy 2007 in their own applications, free of charge.
XML, XML validation, XSLT 1.0, XSLT 2.0, XSLT engine, XQuery 1.0, W3C,