... CSIRO Arch is an open source free enterprise search engine based on Apache Nutch , a popular general purpose search engine that is capable of indexing billions of web pages using clusters of computers. Arch uses Nutch and Solr software and adds additional features to provide a powerful and efficient search engine that is optimized for use in corporate web environments. ... Excellent search quality: Arch has solved the problem of providing good search results for enterprise web sites and intranets! ...