Haystack is an open-source Python framework developed by deepset that enables developers to create production-ready applications powered by Large Language Models (LLMs) and retrieval-augmented generation (RAG) pipelines. It offers a modular architecture, allowing integration with various AI models and tools, including OpenAI, Hugging Face Transformers, Elasticsearch, and more. Haystack supports tasks such as question answering, semantic search, and document retrieval, facilitating the development of sophisticated AI applications. Its flexibility and scalability make it suitable for both research and enterprise use cases.