XMLmind Ebook Compiler (ebookc for short) is a free, open source tool which can turn a set of HTML pages into a self-contained ebookHere “ebook” shall be understood in the widest possible sense.. Supported output formats are: EPUB, Web Help, PDF, RTF, WML, DOCX (MS-Word) and ODT (OpenOffice/LibreOffice).

You can of course use ebookc to create books having a simple structure like novels, but this tool also has all the features needed to create large, complex, reference manuals:

• Builds on topic-oriented structuring like DITA or DocBook 5.1. (Each source HTML page is expected to deal with a single topic.)
• Automatic generation of global and local table of contents.
• Automatic generation of a “back-of-the-book index”.
• Automatic numbering of parts, chapters, appendices, sections, figures, tables, examples and equations.
• Automatic creation of links between some user-specified book divisions.
• Automatic generation of text in cross-references.
• Footnote support.
• Conditional processing (also called profiling).
• Built-in support of XInclude (allows reuse of content at different locations in the book).

Being based on HTML, ebookc relies on CSS to create nicely formatted books and this, even for output formats like PDF and DOCX which are not directly related to HTML and CSS.