OpenSearchServer is an open source, enterprise-grade, very powerful, freely distributed and high-performance search engine (also known as search server) program that provides a collection of high-powered full text search algorithms and uses a web-based interface.
Supports parsing of numerous file formats
The software supports parsing of numerous document formats, including HTML, XHTML, XML, Adobe PDF with OCR, Microsoft Office documents (Word, PowerPoint, Excel, Publisher, Visio), Word, RTF, Plain Text, OpenOffice documents, OCR over images, torrent files, MP3, MP4, FLAC, AIFF, WAV, as well as Ogg Vorbis.
Offers powerful search functions
OpenSearchServer's search functions includes advanced full-text search features, phonetic search, advanced boolean search with query language, clustered results with collapsing and faceting, filter search using sub-requests, geolocation, spell-checking, relevance customization using algebraic functions, and auto-completion.
Provides state-of-the-art indexation functions
Another interesting feature is the indexation function, which supports 18 languages, automatic classification, automatic language recognition, named entity recognition, expression and word synonyms, fields schema with analyzers for each supported language, exporting of indexed terms with frequencies, as well as various filters, such as stripping diacritic from words, lemmatization, n-gram, and shingle.
Powerful crawlers are also implemented
OpenSearchServer also contains powerful crawlers, such as web crawlers for Internet, Intranet and Extranet, filesystem crawlers for both remote and local files, supporting the FTP, SMB, CIFS, NFS, FTPS and SWIFT protocols, sitemap import, screenshot capture, SQL join, session parameters removal, filter inclusion/exclusion using wildcards, as well as database crawler for all supported JDBC databases, including the well known MySQL, PostgreSQL, Microsoft SQL Server, and Oracle.
Many other amazing features
Among other features, OpenSearchServer includes REST APIs (JSON and XML), SOAP web service, monitoring module, index replication, scheduler for management of periodic tasks, as well as Drupal module and a WordPress plugin. The software is supported on all GNU/Linux operating systems, well as on Microsoft Windows and BSD OSes.