Weaviate

Chroma is an open-source AI-native embedding database designed for building LLM applications. It provides simple APIs to store embeddings and perform similarity search, making it ideal for RAG applications.

Milvus is a high-performance open-source vector database built for AI applications. It supports storage, indexing, and similarity search of large-scale vector data, ideal for RAG, recommendation systems, and more.

Qdrant is a high-performance vector database widely used as the retrieval layer for RAG and agent memory search scenarios.

Haystack is an enterprise-grade framework for RAG and search applications, covering document processing, retrieval, generation, and evaluation end to end.