There is a 30-day evaluation license for Saxon-EE which can be used for non-production work, https://www.saxonica.com/download/download.xml https://www.saxonica

There is a 30-day evaluation license for Saxon-EE which can be used for non-production work, https://www.saxonica.com/download/download.xml https://www.saxonica.com/download/download.xml There is also Exselt http://exselt.net http://exselt.net (appears to be down at the moment), I don't think this is Open Source, but it was freely available for download previously.