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No-Code · head to head

Stacker vs Windmill

Stacker logo

Stacker

No-Code

Permissioned portals over data that stays in Airtable, Salesforce or Postgres

From
On request
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

  • Only Windmill has a free tier, so it costs nothing to try first.
  • Each has a real cost: Stacker there is no source export and no self-hosting, so leaving means rebuilding the entire interface and permission model elsewhere, even though the underlying records remain yours.; Windmill free self-hosted tier caps SSO users at 10 and workspaces at 3, requiring Enterprise for larger teams.
  • They diverge on capability: Stacker covers Per-record permissions, Windmill covers Script-to-workflow engine.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Stacker and Windmill actually diverge.

Attributes where Stacker and Windmill differ
AttributeStackerWindmill
Starting priceOn requestFree
Pricing modelquoteopen-source
Free tierNoYes
PlatformsWebweb, api, linux, windows, mac
CategoryNo-CodeAutomation Integration

Identical on both: 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 Stacker

  • Per-record permissions
  • External user portals
  • Live connection to the source
  • Page and layout builder
  • Workflow actions
  • Custom domains and branding
  • User onboarding
  • Role based navigation

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.

Stacker

  • Giving clients a login that shows only their own records inside an internal Airtable basenot Windmill
  • Contractor or franchisee portals where each account must see one slice of a shared datasetnot Windmill
  • Replacing a spreadsheet emailed to partners with a permissioned live view of the same datanot Windmill
  • Putting a usable interface on a Salesforce or Postgres dataset for users who should never see the underlying systemnot Windmill

Windmill

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

Where each one falls short

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

Stacker

  • There is no source export and no self-hosting, so leaving means rebuilding the entire interface and permission model elsewhere, even though the underlying records remain yours.
  • Performance is bounded by the data source, so an Airtable base near its row limit or an API under rate limiting produces a slow portal that no amount of Stacker configuration will fix.
  • Pricing distinguishes internal editors from external portal users, so a portal that succeeds by adding hundreds of light-touch external users can end up costing more than the internal system it fronts.
  • Custom logic is limited to the actions and conditions the builder exposes, so anything resembling a calculation engine or a branching multi-step approval hits a wall and needs an external automation tool bolted on.
  • It is a portal and CRUD tool by design, with no offline mode, no native mobile application and no real reporting layer, so it will not be the only system a growing operation runs.

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

Stacker

On request
  • Stacker$undefined/month
    • Priced by workspace tier with caps on apps and users
    • External portal users charged differently from internal editors
    • Higher tiers add permission depth and support

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 Stacker if

  • You need per-record permissions.
  • You also want external user portals.
Stacker 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 Stacker or Windmill better?
Neither clearly leads. Stacker starts at On request and Windmill at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Stacker or Windmill?
Windmill has a free tier; the other does not. Paid plans start at On request for Stacker and Free for Windmill.
Does Stacker or Windmill run on more platforms?
Stacker runs on Web. Windmill runs on web, api, linux, windows, mac.
Can I use Windmill for free?
Yes. Windmill has a free tier, so you can try it without paying. Stacker starts at On request.
What is Stacker best used for?
Stacker is most often used for giving clients a login that shows only their own records inside an internal airtable base, contractor or franchisee portals where each account must see one slice of a shared dataset, replacing a spreadsheet emailed to partners with a permissioned live view of the same data, putting a usable interface on a salesforce or postgres dataset for users who should never see the underlying system. Of those, giving clients a login that shows only their own records inside an internal airtable base and contractor or franchisee portals where each account must see one slice of a shared dataset are not what Windmill is typically brought in for.
What can Stacker do that Windmill cannot?
Stacker covers Per-record permissions, External user portals, Live connection to the source, Page and layout builder. Windmill covers Script-to-workflow engine, Auto-generated UIs, Self-hosted deployment, Git sync.

Answered from the vendors’ own pages

Stacker: Where does my data live?

In the source you connect: Airtable, Salesforce, HubSpot, Google Sheets or your own Postgres. Stacker reads and writes to it rather than becoming the system of record.

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
Stacker: Can I export the app if I cancel?

No. The data stays in your source system, but the interface, permissions and workflows are Stacker configuration and do not come with you.

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
Stacker: Is it suitable for hundreds of external users?

Technically yes; check the pricing arithmetic first, because external portal users are charged separately and that is where the bill grows.

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
Stacker: Will it replace Airtable?

No, it sits in front of Airtable. If the base itself is at its limits, the fix is moving the data to Postgres rather than changing the portal.

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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