XSLT Processor written in C++. A part of Apache's XML project [Open Source].

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].

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 [...

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

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

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].

Includes a Windows GUI that simplifies designing layouts for complex XML forms and a runtime Engine that merges a layout with XML data to produce a PDF via XSL-FO [Commercial].

XSLT processor for Windows written in C++ [Freeware].

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

Information about Mozilla's native XSLT processor. Includes a FAQ and a list of known bugs.