Vespa

Big-data serving engine fusing vector, text, and structured search.

Vespa is an open-source platform from Yahoo for storing, searching, and serving large datasets with combined vector, lexical, and structured filtering plus in-engine ranking and ML inference. It runs hybrid retrieval and re-ranking at scale in a single system, with first-class support for approximate nearest-neighbor search alongside BM25 and tensor computations. It is notable as a production-grade engine for large RAG and recommendation workloads that need more than a pure vector store.