XSL-FO Debugger is the software for visual debugging of XSL stylesheets. It is based on Altsoft Xml2PDF formatting engine. In short, XSL-FO Debugger takes an XSL-FO file or a pair of XML and XSLT files as an input, follows XSL-FO formatting instructions and generates a PDF document as an output. The resulting PDF file may contain layers for displaying boxes (these are content box, allocation box, border box and padding box), baseline tables and breaks for the groups of FO objects and particular FO objects as well.The XSL-FO specification can be very intricate when you are trying to find out what\'s wrong with this or that FO document. In fact, it is often not so easy to answer many tricky questions that arise when you create a document with a complex structure and thousands of objects. Why are these nested blocks not present on where they should be? What happened to that line? Where on earth is the header? Is it my error or I should send a letter to the producer of my formatter?Xsl-Fo Debugger helps you to avoid spending precious time on re-calculating object parameters, re-reading specification and revising your code. It introduces the visual representation of all basic document areas, baseline tables and breaks generated by the formatter so that you can find irritating shortcomings as fast as possible.What is even more convenient you may select the areas or baselines to be displayed. You may also change the color or opacity of displayed objects as it is described in the following sections. In addition, a separate PDF layer is created for each class of debugged objects, which makes your PDF document interactive and allows turning on/off the particular layers. This feature makes Xsl-Fo Debugger much more applicable and flexible tool. And here the time of your own fantasy and creativity begins!