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APIs · head to head

Formance vs Windmill

Formance logo

Formance

APIs

Open source double-entry ledger and payment orchestration for money-moving software

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: Formance formance holds no money and provides no regulatory cover, so it must be paired with a payments provider or bank, and buyers occasionally mistake a ledger for a treasury system and discover the gap late.; Windmill free self-hosted tier caps SSO users at 10 and workspaces at 3, requiring Enterprise for larger teams.
  • They diverge on capability: Formance covers Double-entry ledger, 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 Formance and Windmill actually diverge.

Attributes where Formance and Windmill differ
AttributeFormanceWindmill
Pricing modelOpen source, no licence feeopen-source
PlatformsLinux, Docker, Kubernetes, Web, APIweb, api, linux, windows, mac
CategoryAPIsAutomation Integration

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 Formance

  • Double-entry ledger
  • Numscript transaction DSL
  • Multi-currency
  • Payments connectivity
  • Reconciliation
  • Cloud offering
  • API and SDKs

Only in Windmill

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

Both cover

  • Self-hosted deployment

What people use each for

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

Formance

  • A marketplace splitting a single customer payment between seller, platform fee and tax that needs the split to be atomic and auditablenot Windmill
  • A fintech whose homegrown balances table produced numbers finance could not reconcile and now needs proper double-entry before an auditnot Windmill
  • A payments team that wants one normalised model across several PSPs so reconciliation is not written separately for eachnot Windmill
  • A company that wants its ledger under a licence it can keep running even if the vendor disappearsnot Windmill

Windmill

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

Where each one falls short

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

Formance

  • Formance holds no money and provides no regulatory cover, so it must be paired with a payments provider or bank, and buyers occasionally mistake a ledger for a treasury system and discover the gap late.
  • Numscript is a domain-specific language your team must learn, and while it makes complex splits expressible it also means transaction logic sits outside the languages your engineers already debug well.
  • Self-hosting a ledger that must never lose or duplicate a transaction is a serious operational commitment covering backups, upgrades and Postgres tuning, which is real cost the zero licence fee hides.
  • Enterprise pricing is not published, so the difference between the free path and the supported path cannot be evaluated without a sales conversation.
  • The company is much smaller than the incumbent alternatives, and while the MIT licence protects the code it does not protect the roadmap, so features on the hosted side may arrive slowly or change direction.

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

Formance

Free
  • Open SourceFree
    • MIT licensed core ledger
    • Numscript transaction DSL
    • Multi-currency tracking
  • Enterprise$undefined/year
    • Managed or private deployment
    • Payments connectivity and reconciliation
    • Support with response commitments

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 Formance if

  • You need double-entry ledger.
  • You want to start without paying.
  • You work on Linux, Docker, Kubernetes, Web, API.
  • You also want numscript transaction dsl.
Formance 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 Formance or Windmill better?
Neither clearly leads. Formance 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, Formance or Windmill?
Formance starts at Free and Windmill at Free.
Does Formance or Windmill run on more platforms?
Formance runs on Linux, Docker, Kubernetes, Web, API. Windmill runs on web, api, linux, windows, mac.
Can I use Formance for free?
Both have a free tier, so you can try either at no cost before committing.
What is Formance best used for?
Formance is most often used for a marketplace splitting a single customer payment between seller, platform fee and tax that needs the split to be atomic and auditable, a fintech whose homegrown balances table produced numbers finance could not reconcile and now needs proper double-entry before an audit, a payments team that wants one normalised model across several psps so reconciliation is not written separately for each, a company that wants its ledger under a licence it can keep running even if the vendor disappears. Of those, a marketplace splitting a single customer payment between seller, platform fee and tax that needs the split to be atomic and auditable and a fintech whose homegrown balances table produced numbers finance could not reconcile and now needs proper double-entry before an audit are not what Windmill is typically brought in for.
What can Formance do that Windmill cannot?
Formance covers Double-entry ledger, Numscript transaction DSL, Multi-currency, Payments connectivity. Windmill covers Script-to-workflow engine, Auto-generated UIs, Git sync, SSO support. Both handle Self-hosted deployment.

Answered from the vendors’ own pages

Formance: Is Formance really open source?

Yes. The core ledger is MIT licensed with full source access and no deployment restrictions.

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
Formance: Does Formance move money?

No. It records and orchestrates movements; the actual payments happen at a PSP or bank you connect.

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
Formance: What does the enterprise version cost?

Not published. It is an annual subscription quoted per customer.

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
Formance: Do I have to use Numscript?

Yes for anything beyond the simplest transfers. It is how multi-party transactions are expressed atomically.

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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