Haystack

Haystack is an open-source NLP framework by deepset for building end-to-end search systems, RAG pipelines, and conversational AI. It provides modular components for document processing, embedding, indexing, retrieval, and generation. Supports all major LLM providers (OpenAI, Anthropic, HuggingFace, local models) and vector databases (Weaviate, Pinecone, Qdrant, Elasticsearch). Pipeline architecture allows combining components into custom workflows. Features include document converters, preprocessors, embedders, retrievers, readers, and generators. Known for production reliability and flexibility. Unlike LlamaIndex which focuses on data indexing, Haystack is more focused on search and question-answering pipelines. Active community and enterprise support available through deepset.