SearchAssist is a simple but practical search engine application that uses a ternary search tree. It uses Java's dynamic loading feature to make the search engine highly customizable, and uses takes Mozilla bookmarks as input. A Swing UI allows users to enter search words and view the results.
Doodle is a desktop search engine for Linux. It searches your hard drive for files using pattern matching on meta-data. It extracts file-format specific meta-data using libextractor and builds a suffix tree to index the files. The index can then be searched rapidly. It is similar to locate, but can take advantage of information such as ID3 tags. It is possible to do full-text indexing using the appropriate libextractor plugins. It also supports using FAM to keep the database up-to-date.
Terrier is software for the rapid development of Web, intranet, and desktop search engines. More generally, it is a modular platform for building large-scale information retrieval applications, providing indexing and probabilistic retrieval functionalities. It comes with a desktop search application.
OpenGrok is a fast and usable source code search and cross reference engine. It helps you search, cross-reference, and navigate your source tree. It can understand various program file formats and version control histories like Mercurial, Bazaar, Git, ClearCase, Perforce, SCCS, RCS, CVS, or Subversion. In other words, it lets you grok (profoundly understand) the source.
Isobel is a framework to build complex information retrieval and analysis systems. Isobel can be functionally divided in two subsytems, Isobel Gatherer (the crawling and filtering subsystem) and Isobel Analyzer (the analysis subsystem). The two subsytems can also be used separately. Isobel Gatherer offers ready-to-use services like content fetching, scheduling, document format conversion, Hyperlink graph storage and analysis, content storage and indexing. A programmer may easily add new services. Isobel Analyzer uses the IBM UIMA architecture to reuse the analysis components developed for this architecture.