Combining vector (semantic) similarity with traditional keyword search (BM25) — vector search finds meaning-similar docs, keyword search catches exact-match queries the embeddings miss.
retrieval
Hybrid Search
Related terms
Tools that implement Hybrid Search
Vespa
RAG · Hosted search engine (not an LLM)
8.2
Yahoo's open-source search engine with vector + sparse retrieval.
Freemium· Free open-source; Vespa Cloud paidlarge-scale searchranking
Weaviate
RAG · Hosted vector DB (not an LLM)
8.4
Open-source vector DB with hybrid search and modules.
Freemium· Free open-source; cloud from $25/moself-hosted RAGhybrid search
Elasticsearch Vector Search
RAG · BYO embeddings (OpenAI, Cohere, Hugging Face, Mistral, Bedrock, Vertex, Azure) plus Elastic's built-in ELSER sparse model and E5 dense model
8.7
Hybrid vector + keyword search in the enterprise-grade Elasticsearch engine
Freemium· Free self-managed open-source core; Elastic Cloud Serverless usage-based (VCU-priced); Elastic Cloud Hosted from ~$95/mo (Standard) with Gold/Platinum/Enterprise tiers; custom Enterprise pricing.RAG chatbot over enterprise docsHybrid semantic + keyword product search