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APIs · head to head

Formance vs Solaris

Formance logo

Formance

APIs

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

From
Free
Rated
-
Full reviewWebsite
Solaris logo

Solaris

APIs

German banking as a service with a full banking licence and a live regulatory problem

From
On request
Rated
-
Full reviewWebsite

The short version

  • Only Formance has a free tier, so it costs nothing to try first.
  • 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.; Solaris baFin appointed a special representative in 2022 and extended the mandate in July 2024, so a partner is joining a bank under active supervisory monitoring, with slower approvals and heavier compliance demands as a direct consequence.
  • They diverge on capability: Formance covers Double-entry ledger, Solaris covers German banking licence.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Formance and Solaris actually diverge.

Attributes where Formance and Solaris differ
AttributeFormanceSolaris
Starting priceFreeOn request
Pricing modelOpen source, no licence feequote
Free tierYesNo
PlatformsLinux, Docker, Kubernetes, Web, APIWeb, API

Identical on both: user rating (Not yet rated), category (APIs).

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 Solaris

  • German banking licence
  • IBAN accounts
  • Card issuing
  • Lending as a service
  • Digital assets and custody
  • SEPA payments
  • KYC and onboarding
  • Deposit protection

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

Solaris

  • A retailer or platform launching a German current account or card product without applying for its own licencenot Formance
  • A fintech that needs deposit taking and lending, which an e-money licence cannot providenot Formance
  • A European business needing German IBANs because customers reject foreign IBANs for salary and direct debitnot Formance
  • A company requiring German statutory deposit protection on customer balances as a product claimnot 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.

Solaris

  • BaFin appointed a special representative in 2022 and extended the mandate in July 2024, so a partner is joining a bank under active supervisory monitoring, with slower approvals and heavier compliance demands as a direct consequence.
  • BaFin fined Solaris EUR 6.5 million in March 2024 for systematically late suspicious activity reports and EUR 500,000 for breaching large exposure limits between January 2022 and March 2024, which is a track record a partner inherits reputationally.
  • Solaris has previously needed BaFin approval before onboarding new corporate clients, which can turn a commercial decision to launch into a regulatory timetable outside your control.
  • The 2024 restructuring involved job cuts and the closure of parts of a business unit, so product lines a partner depends on may not have the engineering behind them that the sales process implies.
  • SBI Holdings acquired majority control in 2025, so strategic direction now sits with a Japanese financial group whose priorities for the European business may differ from the roadmap you were sold.

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

Solaris

On request
  • Solaris banking as a service$undefined/year
    • Quoted per partner, typically setup fee plus monthly platform fee
    • Per account, per card and per transaction charges on top
    • Interchange sharing arrangements negotiated per programme

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 Solaris if

  • You need german banking licence.
  • You work on Web, API.
  • You also want iban accounts.
Solaris review

Questions people ask

Is Formance or Solaris better?
Neither clearly leads. Formance starts at Free and Solaris at On request, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Formance or Solaris?
Formance has a free tier; the other does not. Paid plans start at Free for Formance and On request for Solaris.
Does Formance or Solaris run on more platforms?
Formance runs on Linux, Docker, Kubernetes, Web, API. Solaris runs on Web, API.
Can I use Formance for free?
Yes. Formance has a free tier, so you can try it without paying. Solaris starts at On request.
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 Solaris is typically brought in for.
What can Formance do that Solaris cannot?
Formance covers Double-entry ledger, Numscript transaction DSL, Multi-currency, Payments connectivity. Solaris covers German banking licence, IBAN accounts, Card issuing, Lending as a service.

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.

Solaris: Does Solaris have a real banking licence?

Yes. Solaris SE is a German credit institution, which is why it can offer deposits and lending, unlike e-money based competitors.

Formance: Does Formance move money?

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

Solaris: Is the BaFin action still live?

The special representative appointed in 2022 had the mandate extended in July 2024, and fines were issued in March 2024. Treat supervisory oversight as an active condition in your diligence.

Formance: What does the enterprise version cost?

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

Solaris: Who owns Solaris now?

SBI Holdings of Japan agreed in December 2024 and January 2025 to take a majority stake of over seventy per cent for around EUR 100 million.

Formance: Do I have to use Numscript?

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

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