Softwr

APIs · head to head

Formance vs Swagger UI

Formance logo

Formance

APIs

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

From
Free
Rated
-
Full reviewWebsite
Swagger UI logo

Swagger UI

Developer Tools

Interactive API documentation generated from OpenAPI specs

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.; Swagger UI only as good as the specification: a thin OpenAPI file produces thin documentation
  • They diverge on capability: Formance covers Double-entry ledger, Swagger UI covers OpenAPI rendering.
  • Prices and features above were last checked on 31 August 2026.

Where they differ

Only the attributes on which Formance and Swagger UI actually diverge.

Attributes where Formance and Swagger UI differ
AttributeFormanceSwagger UI
PlatformsLinux, Docker, Kubernetes, Web, APIWeb, Self-hosted, Docker
CategoryAPIsDeveloper Tools

Identical on both: starting price (Free), pricing model (Open source, no licence fee), 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
  • Self-hosted deployment
  • Cloud offering
  • API and SDKs

Only in Swagger UI

  • OpenAPI rendering
  • Try it out
  • Schema display
  • Self-hostable

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 Swagger UI
  • A fintech whose homegrown balances table produced numbers finance could not reconcile and now needs proper double-entry before an auditnot Swagger UI
  • A payments team that wants one normalised model across several PSPs so reconciliation is not written separately for eachnot Swagger UI
  • A company that wants its ledger under a licence it can keep running even if the vendor disappearsnot Swagger UI

Swagger UI

  • Publishing API documentation that stays in step with the specificationnot Formance
  • Letting developers try endpoints before writing any client codenot Formance
  • Internal API discovery across teamsnot 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.

Swagger UI

  • Only as good as the specification: a thin OpenAPI file produces thin documentation
  • Default presentation is dated compared with modern documentation tools
  • Large specifications render slowly and become hard to navigate
  • Try it out against production needs care with authentication and CORS, and is often disabled as a result

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

Swagger UI

Free
  • Swagger UIFree
    • Full functionality
    • Commercial use permitted
    • Community support

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 Swagger UI if

  • You need openapi rendering.
  • You want to start without paying.
  • You work on Web, Self-hosted, Docker.
  • You also want try it out.
Swagger UI review

Questions people ask

Is Formance or Swagger UI better?
Neither clearly leads. Formance starts at Free and Swagger UI at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Formance or Swagger UI?
Formance starts at Free and Swagger UI at Free.
Does Formance or Swagger UI run on more platforms?
Formance runs on Linux, Docker, Kubernetes, Web, API. Swagger UI runs on Web, Self-hosted, Docker.
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 Swagger UI is typically brought in for.
What can Formance do that Swagger UI cannot?
Formance covers Double-entry ledger, Numscript transaction DSL, Multi-currency, Payments connectivity. Swagger UI covers OpenAPI rendering, Try it out, Schema display, Self-hostable.

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.

Swagger UI: Is Swagger UI free?

Yes, open source under the Apache 2.0 licence. SmartBear sells commercial SwaggerHub separately.

Formance: Does Formance move money?

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

Swagger UI: What is the difference between Swagger and OpenAPI?

OpenAPI is the specification format; Swagger is the toolset around it, including Swagger UI. The specification was renamed from Swagger to OpenAPI in 2016.

Formance: What does the enterprise version cost?

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

Swagger UI: Can Swagger UI make real API calls?

Yes, through its try-it-out control, though authentication and CORS configuration often mean it is disabled for production APIs.

Formance: Do I have to use Numscript?

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

Share

Related pages

More on Formance

More on Swagger UI

Keep looking

Other head to heads