Machine Learning · head to head
Haystack vs Milvus
Haystack
Machine Learning
Open-source AI orchestration framework for LLM applications
- From
- Free
- Rated
- -
Milvus
Machine Learning
Open-source vector database for scalable similarity search
- From
- Free
- Rated
- -
The short version
- Each has a real cost: Haystack requires Python programming knowledge for advanced customization; Milvus vector dimensions are capped at 32,768
- They diverge on capability: Haystack covers Modular pipeline composition, Milvus covers Billion-scale vectors.
- Prices and features above were last checked on 30 August 2026.
Where they differ
Only the attributes on which Haystack and Milvus actually diverge.
Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Machine Learning).
What each one covers
Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.
Only in Haystack
- Modular pipeline composition
- Multi-provider LLM support
- Retrieval-augmented generation
- Agent framework
- Memory management
- Observability and debugging
- Kubernetes-ready deployment
Only in Milvus
- Billion-scale vectors
- Multiple index types
- GPU acceleration
- Hybrid search
- Data partitioning
- PyTorch
- TensorFlow
- Hugging Face
What people use each for
The jobs each tool is most often brought in to do.
Haystack
- Building production LLM applications with full controlnot Milvus
- Creating retrieval-augmented generation systemsnot Milvus
- Developing autonomous AI agentsnot Milvus
- Multi-provider LLM orchestrationnot Milvus
- Enterprise AI infrastructurenot Milvus
Milvus
- Self hosting a vector database for semantic searchnot Haystack
- Storing and querying embeddings for retrieval augmented generationnot Haystack
- Similarity search over images, audio or text at scalenot Haystack
Where each one falls short
Documented limitations, not opinions. Every one is a constraint you would hit in normal use.
Haystack
- Requires Python programming knowledge for advanced customization
- Steeper learning curve compared to no-code platforms
- Community support only on free tier may limit enterprise adoption
- Ongoing maintenance dependency for open-source framework
Milvus
- Vector dimensions are capped at 32,768
- A collection is limited to 64 fields, 1,024 partitions and 16 shards
- Only 1 index is allowed per field
- Search returns at most 16,384 vectors as top-k, and nq is capped at 16,384
- Input and output per RPC is capped at 64 MB for insert, search and query
- VARCHAR values are limited to 65,535 characters
- Data loaded into query nodes cannot exceed 90% of available memory
- An instance supports at most 65,536 collections
Pricing, plan by plan
Haystack
Free- Open SourceFree
- Full framework access
- Community Discord support
- GitHub community contributions
- Enterprise Support$undefined/custom
- Private secure engineering support
- Best practices templates and deployment guides
- Flexible services and integrations
Milvus
Free- Open SourceFree
- Full features
- Self-hosted
- Community support
- Zilliz CloudFree
- Managed service
- Free tier available
Which should you pick?
Choose Haystack if
- You need modular pipeline composition.
- You want to start without paying.
- You work on Python, Cloud-agnostic.
- You also want multi-provider llm support.
Choose Milvus if
- You need billion-scale vectors.
- You want to start without paying.
- You work on Linux, Mac, Windows, Web.
- You also want multiple index types.
Questions people ask
- Is Haystack or Milvus better?
- Neither clearly leads. Haystack starts at Free and Milvus at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
- Which is cheaper, Haystack or Milvus?
- Haystack starts at Free and Milvus at Free.
- Does Haystack or Milvus run on more platforms?
- Haystack runs on Python, Cloud-agnostic. Milvus runs on Linux, Mac, Windows, Web.
- Can I use Haystack for free?
- Both have a free tier, so you can try either at no cost before committing.
- What is Haystack best used for?
- Haystack is most often used for building production llm applications with full control, creating retrieval-augmented generation systems, developing autonomous ai agents, multi-provider llm orchestration. Of those, building production llm applications with full control and creating retrieval-augmented generation systems are not what Milvus is typically brought in for.
- What can Haystack do that Milvus cannot?
- Haystack covers Modular pipeline composition, Multi-provider LLM support, Retrieval-augmented generation, Agent framework. Milvus covers Billion-scale vectors, Multiple index types, GPU acceleration, Hybrid search.
Answered from the vendors’ own pages
Haystack: Is Haystack completely free to use?
Yes, the open-source Haystack framework is completely free. deepset offers optional paid enterprise support packages for organizations needing secure engineering support and deployment guidance.
SourceMilvus: How much does Milvus cost?
Milvus is open-source and free to use and modify. The self-hosted version has no licensing cost. Zilliz Cloud (the managed SaaS version) does not publish pricing on the website.
SourceHaystack: What LLM providers does Haystack support?
Haystack supports multiple LLM providers including OpenAI, Anthropic, Mistral, Cohere, and others, allowing teams to avoid vendor lock-in and switch providers as needed.
SourceMilvus: Is there a free or open-source version of Milvus?
Yes, Milvus is fully open-source and available for free. Milvus Lite is a lightweight option for learning and prototyping that can be installed via pip.
SourceHaystack: Can I deploy Haystack in production environments?
Yes, Haystack is designed for production use with Kubernetes-ready pipelines, built-in reliability features, and observability tools for enterprise-scale deployments.
SourceMilvus: Does Milvus offer a managed cloud service?
Yes, Zilliz Cloud is a fully managed Milvus cloud offering with serverless and dedicated cluster options. Pricing must be requested from the company as it is not listed on the public website.
SourceRelated pages
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