Apache Solr is a highly reliable, scalable and fault-tolerant search platform that provides distributed indexing, replication and load-balanced querying, automated failover and recovery, centralized configuration and more. Solr powers the search and navigation features of many of the world's largest internet sites.
Manticore Search is an easy to use open source fast database for search. It helps thousands of companies from small to large, such as Craigslist, to search and filter petabytes of text data on a single or hundreds of nodes, do stream full-text filtering, add auto-complete, spell correction, more-like-this, faceting and other search-related technologies to their websites and applications.
ZincSearch is a lightweight, fast, and modern search engine built in Go. It provides full-text search capabilities with a simple REST API, making it an excellent alternative to Elasticsearch for smaller to medium-scale applications. ZincSearch offers easy deployment, low resource consumption, and compatibility with Elasticsearch APIs.