XSLT Reference : Good to Know
 
Good to Know
The below tools are useful for debugging and testing custom code in a controlled environment:
*For XSLT: XSLT fiddle
*For C#: .NET Fiddle
*For JavaScript/HTML/CSS: JSFiddle
Difference between HTML and XHTML
Useful tool for generating API documentation: Doxygen
Tool ePublisher uses to clean HTML documents: Tidy. If you need to customize Tidy, refer to the Tidy Quick Reference