Haystack — Production RAG & Agent Framework

Introduction

Haystack is a production-grade framework for building RAG pipelines, AI agents, and search systems. Created by deepset, it provides composable building blocks that snap together into complex AI applications — from simple question answering to multi-step agents with tool use.

Core capabilities:

• Composable Pipelines — Build AI workflows by connecting modular components: retrievers, readers, generators, rankers, and more. Type-safe connections prevent runtime errors
• RAG Out of the Box — Pre-built components for document indexing, embedding, retrieval, and generation. Support for 15+ vector stores and all major embedding models
• AI Agents — Build agents with tool use, planning, and multi-step reasoning. Agents can call pipelines as tools, enabling complex nested workflows
• Model Agnostic — Works with OpenAI, Anthropic, Google, Cohere, Hugging Face, Ollama, and any custom model. Switch providers without rewriting pipeline logic
• Document Processing — Convert PDFs, DOCX, HTML, and more into indexed documents. Built-in preprocessing, splitting, and cleaning
• Evaluation — Built-in evaluation framework to measure RAG quality with metrics like faithfulness, relevance, and context precision
• Production Ready — Serializable pipelines, async execution, streaming, and deployment-ready with REST API generation

18,000+ GitHub stars. Used in production by enterprises for knowledge management, customer support, and document intelligence.

FAQ

Q: How is Haystack different from LangChain? A: Haystack focuses on type-safe, composable pipelines with strong production guarantees. LangChain is more flexible but less opinionated. Haystack pipelines are serializable (save/load as YAML) and have built-in evaluation. Choose Haystack for production RAG, LangChain for rapid prototyping.

Q: Can I use it with local models? A: Yes. Haystack supports Ollama, Hugging Face Transformers, and any OpenAI-compatible local server. Run your entire pipeline offline.

Q: Does it support streaming? A: Yes. Haystack 2.x has built-in streaming support. Responses stream token by token from generators through the pipeline to your application.

Q: Is it free? A: Haystack is fully open source (Apache 2.0). deepset offers a commercial platform (deepset Cloud) for managed deployment, but the framework itself is free.

Works With

• OpenAI / Anthropic / Google / Cohere / Ollama for LLMs
• Weaviate / Qdrant / Pinecone / Chroma / Elasticsearch for vector stores
• Hugging Face models for embeddings and reranking
• FastAPI for REST API deployment
• Docker / Kubernetes for production scaling