Xapian

Xapian is an Open Source Search Engine Library, released under the GPL. It's written in C++, with bindings to allow use from Perl, Python, PHP, Java, Tcl, C# and Ruby (so far!)

Xapian is a highly adaptable toolkit which allows developers to easily add advanced indexing and search facilities to their own applications. It supports the Probabilistic Information Retrieval model and also supports a rich set of boolean query operators.

Links

• http://xapian.org/
• http://en.wikipedia.org/wiki/Xapian
• http://docs.huihoo.com/xapian/