The DjVu Reference Library 3.5 was released by Lizardtech under the GNU General Public License version 2. DjVuLibre-3.5 was developed by Leon Bottou and others as a "Derived Work" of the DjVu Reference Library 3.5. As such, it is also subject to the GNU General Public License version 2.
Several patents apply to two very specific aspects of DjVu and DjVuLibre. The patents cover a particular aspect of the ZP-coder (the arithmetic coder used in DjVu and implemented in libdjvu/ZPCodec.cpp)...
Regain is a Java search engine based on Jakarta Lucene. It provides indexing and searching files for plenty of formats (HTML,XML,doc(x),xls(x),ppt(x),oo,PDF,RTF,mp3,mp4,Java). A TagLibrary eases integrating search results in your JSP based web page.