A debugger for xsl/xslt stylesheets which has functionality similar to a Unix/Linux "gdb". This is achieved using libxml2 and libxslt (gnome-xml).
A summary of commands types are
Help, running, template, breakpoint and node viewing
A GUI front-end to xsldbg is available for
* Qt5 called qxsldbg
* kate editor plugin called kxsldbg
A package for XEmacs is also available called xsldbg-mode