Xslty is a simple command-line utility that transforms XML using XSLT 2.0 and outputs it to stdout. I made it to scratch my own itch, so it might not suit your needs, but it probably will if you just need to transform XML.
XSLTy requires PhantomJS to be installed. This is because XSLTy uses Saxon CE to parse XSLT 2.0, and that's a browser library.
In case you don't have PhantomJS installed, you can install it easy on OSX:
brew update && brew install phantomjs
See PhantomJS download page for other platforms
npm install xslty -g
xslty source.xml style.xsl
The order of parameters is important. The source XML has to always go first, followed by the XSLT transformation file. Any result of the transformation will come out to stdout, while errors will come out to stderr, as expected.
Mozilla Public License 2.0