Chili Search is described as 'replaces the WordPress default search with a lightning fast, full-ajax and accurate search' and is an app in the Online Services category. There are more than 10 alternatives to Chili Search for a variety of platforms, including Online / Web-based, Self-Hosted solutions, Windows, Linux and Mac. The best alternative is elasticsearch, which is free. Other great apps like Chili Search are MeiliSearch (Free, Open Source), Algolia (Free Personal), Apache Solr (Free, Open Source) and Sphinx (search engine) (Free).
Solr is an open source enterprise search server based on Lucene search library, with XML/HTTP and JSON APIs. Its major features include powerful full-text search, hit highlighting, faceted search, dynamic clustering, database integration, and rich document handling.
Sphinx is a software search engine designed with indexing database content in mind. It currently supports MySQL, PostgreSQL, and ODBC-compliant databases as data sources natively. Other data sources can be indexed via pipe in a custom XML format.