Full-text search system. You can search lots of documents for some documents
including specified words. If you run a web site, it is useful as your own
search engine for pages in your site. Also, it is useful as search utilities
of mail boxes and file servers.

The characteristic of Hyper Estraier is the following.
  * High performance of search
  * High scalability of target documents
  * Perfect recall ratio by N-gram method
  * Phrase search, attribute search, and similarity search
  * Multilingualism with Unicode
  * Independent of file format and repository
  * Simple and powerful API
  * Supporting P2P architecture

WWW: http://hyperestraier.sourceforge.net/