Includes an XSLT Processor written in Python by FourThought LLC [Open Source].

Uses XSL formatting objects to dynamically create customized PDF, POSTSCRIPT, HTML, GIF, JPEG, or PNG files from XML data [Commercial].

XSLT C library developed for the Gnome project [Open Source, MIT].

DGXT is an optimized software-based XSLT interpreter that is cross-platform and fully compliant with the current XSL specification. The XA35 XML Accelerator is a hardware-based solution that speeds XSLT, XPath, XSD (Schema validation) by 30X or more [...

Contains an XSLT engine, which fully implements the XSLT 1.0 standard [Freeware].

A library of TeX macros which can be used to process an XML document which results from an XSL transformation to FO (formatting objects) [LaTex].

A letter, report, and output generator for XSLT/XSLFO documents. GUI Designer for stylesheets, plus an Engine to create XSLT, XSLFO, PDF, XHTML, and PCL5. [Commercial].

ShoXS is a Shorter Syntax for XSL and this site provides some tools to read XSL files, convert and edit in ShoXS then convert back and save in XSL [Open Source, GPL].

Java XSLT processor developed by Michael Kay [Open source, MPL].

Drag and drop XSLT Editor that doesn't require knowledge of XSLT syntax. Developer edition is free [Commercial].