Apache Solr

Open-source enterprise search platform built on Apache Lucene, supporting full-text, vector, and geospatial search. Index documents via REST API using JSON, XML, or CSV, query over HTTP, and receive structured results with faceting, highlighting, and near real-time updates.

Apache Solr powers search and navigation at many of the world's largest sites, including Netflix, eBay, DuckDuckGo, Salesforce, Adobe, and Bloomberg. It differentiates from lighter search tools with SolrCloud, a distributed architecture built on Apache ZooKeeper that handles sharding, replication, failover, and rebalancing out of the box, scaling to billions of documents.

Key capabilities:

• Multi-modal search: full-text, vector (semantic), and geospatial in one platform
• SolrCloud for distributed indexing, replication, load balancing, and fault tolerance
• Faceted search, spell-check, auto-complete, and configurable relevance tuning
• Schema or schemaless modes, with Apache Tika for indexing PDF, Word, and other rich content
• Built-in admin UI, JMX metrics, and Docker or Kubernetes deployment options

Use cases span product and e-commerce search, log and log-analytics search, content management and document discovery, and location-aware applications. Developers integrate via HTTP and standard formats, with optional native clients, and can tune queries, analyzers, and caching without leaving the platform.