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Machine Learning · head to head

Milvus vs OpenRouter

Milvus logo

Milvus

Machine Learning

Open-source vector database for scalable similarity search

From
Free
Rated
-
Full reviewWebsite
OpenRouter logo

OpenRouter

Machine Learning

Unified API gateway routing requests across 500+ models from 80+ providers

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Milvus vector dimensions are capped at 32,768; OpenRouter no free tier; all usage incurs cost
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Milvus and OpenRouter actually diverge.

Attributes where Milvus and OpenRouter differ
AttributeMilvusOpenRouter
Pricing modelfreemiumusage-based
PlatformsLinux, Mac, Windows, WebAPI, Web
Founded2017Unknown

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 Milvus

  • Billion-scale vectors
  • Multiple index types
  • GPU acceleration
  • Hybrid search
  • Data partitioning
  • PyTorch
  • TensorFlow
  • Hugging Face

Only in OpenRouter

Nothing recorded that Milvus does not also cover.

What people use each for

The jobs each tool is most often brought in to do.

Milvus

  • Self hosting a vector database for semantic searchnot OpenRouter
  • Storing and querying embeddings for retrieval augmented generationnot OpenRouter
  • Similarity search over images, audio or text at scalenot OpenRouter

OpenRouter

  • Multi-model applications optimising for cost or performancenot Milvus
  • Provider-agnostic deployments avoiding vendor lock-innot Milvus
  • Enterprise applications with custom data policies and provider requirementsnot Milvus
  • Development workflows testing multiple models without code changesnot Milvus

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

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

OpenRouter

  • No free tier; all usage incurs cost
  • Pricing varies by model; specific rates not published on main site without account access
  • Adds latency through additional routing layer compared to direct provider APIs
  • Dependent on upstream provider uptime and API compatibility

Pricing, plan by plan

Milvus

Free
  • Open SourceFree
    • Full features
    • Self-hosted
    • Community support
  • Zilliz CloudFree
    • Managed service
    • Free tier available

OpenRouter

Free
  • FreeFree
    • 50 requests per day
    • Access to 25+ free models across 4 providers
    • Community support
  • Pay-as-you-go$null/variable
    • 5.5% platform fee on inference costs
    • Access to 500+ models across 80+ providers
    • Email support
  • Enterprise$null/custom
    • Negotiable platform fees
    • 200,000 USD of list price inference per month with no fees, then 5% fee after
    • SSO/SAML support

Which should you pick?

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.
Milvus review

Choose OpenRouter if

  • You want to start without paying.
  • You work on API, Web.
OpenRouter review

Questions people ask

Is Milvus or OpenRouter better?
Neither clearly leads. Milvus starts at Free and OpenRouter at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Milvus or OpenRouter?
Milvus starts at Free and OpenRouter at Free.
Does Milvus or OpenRouter run on more platforms?
Milvus runs on Linux, Mac, Windows, Web. OpenRouter runs on API, Web.
Can I use Milvus for free?
Both have a free tier, so you can try either at no cost before committing.
What is Milvus best used for?
Milvus is most often used for self hosting a vector database for semantic search, storing and querying embeddings for retrieval augmented generation, similarity search over images, audio or text at scale. Of those, self hosting a vector database for semantic search and storing and querying embeddings for retrieval augmented generation are not what OpenRouter is typically brought in for.
What can Milvus do that OpenRouter cannot?
Milvus covers Billion-scale vectors, Multiple index types, GPU acceleration, Hybrid search.

Answered from the vendors’ own pages

Milvus: 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.

Source
OpenRouter: How much does OpenRouter charge?

OpenRouter charges a 5.5% platform fee on top of the actual inference costs from selected models. Customers purchase credits on a pay-as-you-go basis with no subscriptions or minimum spend requirements.

Source
Milvus: 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.

Source
OpenRouter: Is there a free tier?

Yes. OpenRouter offers a free tier with 50 requests per day and access to 25+ free models across 4 providers. The free tier provides community support only.

Source
Milvus: 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.

Source
OpenRouter: What does the Enterprise plan include?

The Enterprise plan includes 200,000 USD of list price inference per month at no cost, with a 5% platform fee applied to usage above that threshold. It also includes SSO/SAML support, contractual SLAs, and dedicated support with a shared Slack channel.

Source
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