Itzam/Sharp is a C# class library for creating and manipulating keyed-access database files containing variable-length, random access records. Information is referenced by a user-defined key value; indexes may be combined with or separate from data. Itzam/Sharp implements the Itzam engine (see Itzam/Core and Itzam/Java) in 100% managed C#. At 32K, the Itzam/Sharp engine is both small and powerful, and it works with any .NET language, including F# and Visual Basic.
Associations Indexing Service (AIS) was originally done as an extension of human memory for tagging (storing under personal keywords and associations) resources, URIs, bookmarks, and memos (for fast access to the information in future) by using the same keywords or queries, similar to popular search engines. It can be seen as a local search engine, used as an automatic indexer of big file hierarchies (e.g. personal archives or files repositories). It is based on Lucene, so the application will remain very fast with any size index.
Basenji is an indexing and search tool designed for easy and fast indexing of media collections. Once indexed, removable media such as CDs and USB sticks can be browsed and searched for specific files very quickly, without actually being connected to the computer. Besides file hierarchies and audio track listings, Basenji also presents extracted metadata (image dimensions, mp3 tags etc.) and content previews of indexed media in a clean and straightforward user interface.
XapianFu is a Ruby library for working with Xapian databases. It builds on the GPL licensed Xapian Ruby bindings, but provides an interface more in-line with "The Ruby Way"(tm) and is considerably easier to use. For example, you can work almost entirely with Hash objects, and XapianFu will handle converting the Hash keys into Xapian term prefixes when indexing and when parsing queries. It also handles storing and retrieving hash entries as Xapian::Document values. XapianFu basically gives you a persistent Hash with full text indexing (and ACID transactions).
Multi-Dimensional Data Structure (mdds) is a C++ library that includes a collection of various data structures designed to efficiently store and query multi-dimensional data for various filtering criteria. Different structures are optimized for different query needs. The library is provided as a header only, meaning that programs do not need to link to any additional shared library in order to use these data structures. The data structures are all available as C++ templates.
Stupa is an associative search engine. It lets you search related documents with high performance and high precision. Since document data and inverted indexes are kept in memory, Stupa reflects updates of documents in search results in real time. A server implementation of Stupa is possible by using Thrift.