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Automation Integration · head to head

Prefect vs Windmill

Prefect logo

Prefect

Automation Integration

Python-first workflow orchestration that heals itself

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: Prefect limited to Python-based workflows; other languages require API calls; Windmill free self-hosted tier caps SSO users at 10 and workspaces at 3, requiring Enterprise for larger teams.
  • They diverge on capability: Prefect covers Python function decorators, Windmill covers Script-to-workflow engine.

Where they differ

Only the attributes on which Prefect and Windmill actually diverge.

Attributes where Prefect and Windmill differ
AttributePrefectWindmill
Pricing modelFreemium with per-user and usage-based tiersopen-source
PlatformsCloud, Self-hosted, VPCweb, api, linux, windows, mac

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

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 Prefect

  • Python function decorators
  • Automatic resilience
  • Flexible deployment
  • Observable execution
  • Multiple scheduling
  • Webhooks
  • Open-source core

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.

Prefect

  • Orchestrating data pipeline workflows in Pythonnot Windmill
  • Managing ML model training and inference jobsnot Windmill
  • Building ETL and event-driven automationnot Windmill
  • Monitoring and alerting on workflow healthnot Windmill

Windmill

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

Where each one falls short

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

Prefect

  • Limited to Python-based workflows; other languages require API calls
  • Hobby free tier severely limited for production use
  • Team plan billing per user scales quickly with team size
  • Less visual workflow builder compared to some competitors
  • Smaller ecosystem of pre-built connectors than alternatives

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

Prefect

Free
  • HobbyFree
    • 2 users and 5 deployments
    • 500 minutes serverless monthly
    • 7-day run retention
  • Starter$100/month
    • 3 users and 20 deployments
    • 75 hours serverless compute
    • Bring-your-own infrastructure
  • Team$100/user/month
    • 4-8 users per plan tier
    • 100 deployments
    • 225 hours serverless monthly
  • Enterprise$null/custom
    • SSO and SAML authentication
    • Role-based access control
    • Multiple workspaces

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 Prefect if

  • You need python function decorators.
  • You want to start without paying.
  • You work on Cloud, Self-hosted, VPC.
  • You also want automatic resilience.
Prefect 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 Prefect or Windmill better?
Neither clearly leads. Prefect 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, Prefect or Windmill?
Prefect starts at Free and Windmill at Free.
Does Prefect or Windmill run on more platforms?
Prefect runs on Cloud, Self-hosted, VPC. Windmill runs on web, api, linux, windows, mac.
Can I use Prefect for free?
Both have a free tier, so you can try either at no cost before committing.
What is Prefect best used for?
Prefect is most often used for orchestrating data pipeline workflows in python, managing ml model training and inference jobs, building etl and event-driven automation, monitoring and alerting on workflow health. Of those, orchestrating data pipeline workflows in python and managing ml model training and inference jobs are not what Windmill is typically brought in for.
What can Prefect do that Windmill cannot?
Prefect covers Python function decorators, Automatic resilience, Flexible deployment, Observable execution. Windmill covers Script-to-workflow engine, Auto-generated UIs, Self-hosted deployment, Git sync.

Answered from the vendors’ own pages

Prefect: What is included in the Hobby free plan?

Hobby includes 2 users, 5 deployments, 500 minutes of serverless compute monthly, and 7-day run retention.

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
Prefect: What is the difference between Starter and Team plans?

Starter is $100/month for 3 users and 20 deployments. Team is $100 per user per month for 4-8 users and 100 deployments.

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
Prefect: Can I deploy Prefect in my own infrastructure?

Yes, Starter and higher plans support bring-your-own-compute infrastructure and VPC deployments.

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
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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