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APIs · head to head

Swagger/OpenAPI vs Windmill

Swagger/OpenAPI logo

Swagger/OpenAPI

APIs

API specification and documentation framework using OpenAPI standard

From
Free
Rated
-
Full reviewWebsite
Windmill logo

Windmill

Automation Integration

Open-source developer platform for building scripts, workflows, and internal apps

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Swagger/OpenAPI the OpenAPI Specification itself is licensed under Apache License 2.0 and free to use; SwaggerHub is a separate paid tool built on top of it; Windmill free self-hosted tier caps SSO users at 10 and workspaces at 3, requiring Enterprise for larger teams.
  • They diverge on capability: Swagger/OpenAPI covers OpenAPI Specification, Windmill covers Script-to-workflow engine.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Swagger/OpenAPI and Windmill actually diverge.

Attributes where Swagger/OpenAPI and Windmill differ
AttributeSwagger/OpenAPIWindmill
Pricing modelfreemiumopen-source
PlatformsWeb, CLI, Desktopweb, api, linux, windows, mac
CategoryAPIsAutomation Integration
Founded2001Unknown

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated).

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 Swagger/OpenAPI

  • OpenAPI Specification
  • Interactive Documentation
  • Code Generation
  • GitHub
  • GitLab
  • Jenkins
  • IDE plugins
  • Web support

Only in Windmill

  • Script-to-workflow engine
  • Auto-generated UIs
  • Self-hosted deployment
  • Git sync
  • SSO support
  • Audit logs

What people use each for

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

Swagger/OpenAPI

  • API Developmentnot Windmill
  • API Gatewaynot Windmill
  • API Testingnot Windmill
  • API Documentationnot Windmill
  • Microservicesnot Windmill

Windmill

  • Turning ad-hoc scripts into scheduled jobs and APIsnot Swagger/OpenAPI
  • Building internal tools from existing Python/TypeScript codenot Swagger/OpenAPI
  • Self-hosted automation for engineering teamsnot Swagger/OpenAPI
  • Orchestrating multi-language workflowsnot Swagger/OpenAPI

Where each one falls short

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

Swagger/OpenAPI

  • The OpenAPI Specification itself is licensed under Apache License 2.0 and free to use; SwaggerHub is a separate paid tool built on top of it

Windmill

  • Free self-hosted tier caps SSO users at 10 and workspaces at 3, requiring Enterprise for larger teams.
  • Compute unit and seat-based pricing (developer vs. operator seats, worker compute units) adds pricing complexity beyond a flat monthly fee.
  • Email triggers are capped at 100/day on the free tier, limiting event-driven use cases without upgrading.
  • Smaller ecosystem of pre-built integrations compared to more established automation tools like n8n.

Pricing, plan by plan

Swagger/OpenAPI

Free
  • Open SourceFree
    • OpenAPI specification
    • Community tools
  • SwaggerHub FreeFree
    • Cloud editor
    • API mocking
    • API testing
  • SwaggerHub Pro$75/monthly
    • Team collaboration
    • Advanced mocking
    • Analytics

Windmill

Free
  • Free / Open-sourceFree
    • Unlimited executions
    • Self-hosted deployment
    • Max 10 users with SSO
  • Enterprise$120/month
    • Unlimited executions and workspaces
    • Uncapped SSO seats
    • 24/7 priority support (3-hour response)

Which should you pick?

Choose Swagger/OpenAPI if

  • You need openapi specification.
  • You want to start without paying.
  • You work on Web, CLI, Desktop.
  • You also want interactive documentation.
Swagger/OpenAPI review

Choose Windmill if

  • You need script-to-workflow engine.
  • You want to start without paying.
  • You work on web, api, linux, windows, mac.
  • You also want auto-generated uis.
Windmill review

Questions people ask

Is Swagger/OpenAPI or Windmill better?
Neither clearly leads. Swagger/OpenAPI starts at Free and Windmill at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Swagger/OpenAPI or Windmill?
Swagger/OpenAPI starts at Free and Windmill at Free.
Does Swagger/OpenAPI or Windmill run on more platforms?
Swagger/OpenAPI runs on Web, CLI, Desktop. Windmill runs on web, api, linux, windows, mac.
Can I use Swagger/OpenAPI for free?
Both have a free tier, so you can try either at no cost before committing.
What is Swagger/OpenAPI best used for?
Swagger/OpenAPI is most often used for api development, api gateway, api testing, api documentation. Of those, api development and api gateway are not what Windmill is typically brought in for.
What can Swagger/OpenAPI do that Windmill cannot?
Swagger/OpenAPI covers OpenAPI Specification, Interactive Documentation, Code Generation, GitHub. Windmill covers Script-to-workflow engine, Auto-generated UIs, Self-hosted deployment, Git sync.

Answered from the vendors’ own pages

Swagger/OpenAPI: Is Swagger UI free to use?

Swagger UI is an open source tool with source code publicly available on GitHub at no cost. It is one of thousands of free open source projects in the Swagger ecosystem.

Source
Windmill: What does Windmill cost?

Windmill's Free and Open-source edition is $0/month for self-hosted use with unlimited executions, while Enterprise starts at $120/month with unlimited workspaces and uncapped SSO seats, priced further by developer/operator seats and compute units.

Source
Swagger/OpenAPI: What commercial Swagger products are available beyond the open source tools?

Swagger offers Swagger for Teams for streamlined API workflow with interactive editors and hosted documentation, and Swagger Enterprise for organizations needing secure on-premise or cloud-based environments. Specific pricing requires contacting sales.

Source
Windmill: Is there a free plan and what are its limits?

The free self-hosted plan supports unlimited executions but caps SSO at 10 users, workspaces at 3, groups/permissions at 4, and email triggers at 100 per day.

Source
Swagger/OpenAPI: Are there commercial versions that build on the open source Swagger tools?

Yes, commercial Swagger products integrate the core functionality of Swagger open source tools (Editor, UI, and Codegen) with advanced capabilities for team collaboration, standards enforcement, and enterprise features.

Source
Windmill: How is usage metered on Windmill Enterprise?

Enterprise usage is metered through seats (developer seats at $20/month, operator seats at $10/month) and compute units, e.g. $100/month for 2 standard-worker compute units.

Source
Swagger/OpenAPI: Is there a trial available for Swagger commercial products?

A Start Trial call-to-action is available on the Swagger website, but specific trial duration and terms are not disclosed on the product pages.

Source
Windmill: What happens to a self-hosted Windmill deployment if the company shuts down?

The pricing page addresses this directly as an FAQ topic, noting that self-hosted applications built on the open-source edition can continue running independently of Windmill the company.

Source
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