xindy is an index processor that can be used to generate book-like indexes for arbitrary document-preparation systems. This includes systems such as TeX and LaTeX, the roff-family, SGML/XML-based systems (e.g., HTML) that process some kind of text and generate indexing information. The kernel system is not fixed to any specific system, but can be configured to work together with such systems. In comparison to other index processors xindy has several powerful features that make it an ideal framework for describing and generating complex indices, addressing especially international indexing. Have a look at xindy's Overview that describes its most important features!