OpenSearch - OpenSearch is a community-driven, open source search and analytics suite derived from Apache 2.0 licensed Elasticsearch 7.10.2 & Kibana 7.10.2. It consists of a search engine daemon, and a visualization and user interface, OpenSearch Dashboards.

Wikipedia - Wikipedia is a free online encyclopedia, created and edited by volunteers around the world and hosted by the Wikimedia Foundation.

Sphinx Search - Sphinx is an open source full text search server, designed with performance, relevance (search quality), and integration simplicity in mind. Sphinx lets you either batch index and search data stored in files, an SQL database, NoSQL storage.

Encyclopædia Britannica - Explore the fact-checked online encyclopedia from Encyclopaedia Britannica with hundreds of thousands of objective articles, biographies, videos, and images from experts.

Apache Lucene - High-performance, full-featured text search engine library written entirely in Java.

Kiwix - Kiwix enables you to have the whole Wikipedia at hand wherever you go!