Haystack

Haystack is an open-source Python framework for building production-grade LLM applications — retrieval-augmented generation (RAG) pipelines, question-answering systems, and semantic search — on top of your own documents.

It provides composable building blocks (document stores, retrievers, generators, pipelines) so you assemble a RAG system from tested components rather than wiring an LLM to a vector database from scratch, with integrations across major vector databases and LLM providers.

Maintained by deepset; commonly used by teams building an internal knowledge-base chatbot or document Q&A system who want a structured framework rather than a fully custom pipeline.