Apache Lucene: Open-source Java text search library for structured, full-text, faceting, nearest-neighbor, spell correction, and query suggestions. Powers Elasticsearch, Solr, Hadoop, and many custom search applications. github.com/apache/lucene

Elasticsearch: Open-source distributed search and analytics engine built on Lucene for speed, scalability, and ease of use. Used by e-commerce, news, and government organizations. Check license for your use case. github.com/elastic/elas...