OpenSearch
Description: OpenSearch is an open source search engine software project that is based on Elasticsearch and Apache 2.0 licensed. It provides RESTful search and analytics APIs suitable for building search applications.
Type: software
Pricing: Open Source
Xapian
Description: Xapian is an open source search engine library that allows developers to add advanced searching capabilities to their applications. It supports features like full text and boolean search, spelling correction, query expansion, relevance ranking, and more.
Type: software
Pricing: Open Source