Haystack (OSS)
Open source framework from deepset for building RAG pipelines, agents and search over private data with tracing and eval integrations.
Overview
Haystack is a modular Python framework for retrieval augmented generation, agents and production search. You compose nodes for indexing, retrieval, reranking, prompting, tool use and output formatting, then run pipelines locally or in containers. It supports vector stores, BM25, hybrid search, document stores, streaming chunkers and common embedding backends, so teams can standardize on one abstraction while swapping components.
Tracing hooks and evaluation modules integrate with deepset Studio and other observability tools to compare retrievers, prompts and models using automatic and rubric based metrics. Starter templates cover chat over docs, semantic search and extraction, while tutorials help teams connect cloud object stores and handle chunking, deduplication and metadata filters. Because it is Apache licensed, Haystack fits regulated environments that prefer self hosted stacks, and it pairs well with deepset Cloud for managed runtimes when needed.
Key features
- Pipelines for RAG QA and agents
- Document stores vector DBs hybrid search
- Integration with rerankers and LLMs
- Evaluation and tracing modules
- Templates for chat over docs
- Streaming chunkers and metadata filters
- CLI and Python SDK for devs
- Self hosted friendly with OSS license
Best for
- Stand up chat over wikis and PDFs
- Unify search across knowledge bases
- Prototype agents that call tools
- Compare retrievers and prompts
- Build governed RAG inside VPC
- Automate extraction and routing
- Serve semantic answers in apps
- Teach RAG patterns to teams
Capabilities
Nodes and pipelines
Chain retrievers rerankers LLMs and tools into reproducible pipelines with config and code.
Tracing and evals
Measure quality and latency with built in evals and traces that plug into observability.
Backends and stores
Switch vector DBs models and chunkers without rewriting application code.
APIs and templates
Use starters for chat over docs and deploy as services or batch jobs.
Frequently Asked Questions
How is Haystack licensed and priced?
Haystack is open source and free to use under a permissive license, managed deepset Platform tiers are optional for hosted runtimes.
Does it work with my vector database?
Yes, integrations exist for popular vector stores and traditional indexes so you can run hybrid search.
Can I evaluate changes before release?
Built in eval and tracing help compare prompts retrievers and models with shareable reports.
Is there a quick way to start?
Templates and tutorials cover chat over documents semantic search and extraction with minimal setup.
Can I deploy in a private VPC?
Yes, Haystack runs self hosted and is commonly deployed in private cloud or on premises.
