Haystack is an open-source AI orchestration framework from deepset for building production applications with language models, retrieval, tools, and agents. It is built around modular components and pipelines that can be combined to create RAG systems, search applications, question-answering services, and increasingly agentic workflows.

Developers can connect model providers, document stores, retrievers, embedders, rankers, generators, converters, and custom components into explicit pipelines. This component-based architecture makes it possible to swap infrastructure or experiment with different retrieval and generation strategies without rewriting the entire application.

Haystack is useful for teams building document-grounded assistants and other production AI systems where retrieval quality and pipeline control matter. It provides a mature framework for moving from experimentation to maintainable services while retaining flexibility over models, vector databases, preprocessing, evaluation, and application-specific components.