Softwr

APIs · head to head

Solaris vs Stainless

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
Stainless logo

Stainless

APIs

Generates client SDKs, API docs, and MCP servers from an OpenAPI spec

From
Free
Rated
-
Full reviewWebsite

The short version

  • Only Stainless has a free tier, so it costs nothing to try first.
  • Each has a real cost: 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.; Stainless starter and Pro plan prices are not published and require contacting the company.
  • They diverge on capability: Solaris covers German banking licence, Stainless covers SDK generation.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Solaris and Stainless actually diverge.

Attributes where Solaris and Stainless differ
AttributeSolarisStainless
Starting priceOn requestFree
Pricing modelquotefreemium
Free tierNoYes

Identical on both: platforms (Web, API), 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 Solaris

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

Only in Stainless

  • SDK generation
  • MCP server generation
  • Docs site generation
  • Webhooks and streaming support
  • Automated unit tests
  • Git integration

What people use each for

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

Solaris

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

Stainless

  • Generating typed SDKs for a public APInot Solaris
  • Producing an MCP server from an existing OpenAPI specnot Solaris
  • Building an API documentation site alongside client librariesnot Solaris
  • Giving open-source APIs a free SDK generation pathnot Solaris

Where each one falls short

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

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.

Stainless

  • Starter and Pro plan prices are not published and require contacting the company.
  • The free plan caps APIs at 25 endpoints, which excludes larger production APIs.
  • Overage charges apply per SDK/endpoint/month once limits are exceeded, which can make costs unpredictable at scale.

Pricing, plan by plan

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

Stainless

Free
  • FreeFree
    • Up to 5 generators (SDKs, docs, or MCP servers)
    • 5 seats
    • APIs with 25 or fewer endpoints
  • Starter$undefined/mo
    • Unlimited generators
    • Expanded seats
    • Private SDKs of any size
  • Pro$undefined/mo
    • Custom enterprise features and pricing
  • Enterprise$undefined/mo
    • Dedicated support
    • SOC 2 compliance reports
    • Purchase order/invoicing with negotiable terms

Which should you pick?

Choose Solaris if

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

Choose Stainless if

  • You need sdk generation.
  • You want to start without paying.
  • You work on web, api.
  • You also want mcp server generation.
Stainless review

Questions people ask

Is Solaris or Stainless better?
Neither clearly leads. Solaris starts at On request and Stainless at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Solaris or Stainless?
Stainless has a free tier; the other does not. Paid plans start at On request for Solaris and Free for Stainless.
Does Solaris or Stainless run on more platforms?
Solaris runs on Web, API. Stainless runs on web, api.
Can I use Stainless for free?
Yes. Stainless has a free tier, so you can try it without paying. Solaris starts at On request.
What is Solaris best used for?
Solaris is most often used for a retailer or platform launching a german current account or card product without applying for its own licence, a fintech that needs deposit taking and lending, which an e-money licence cannot provide, a european business needing german ibans because customers reject foreign ibans for salary and direct debit, a company requiring german statutory deposit protection on customer balances as a product claim. Of those, a retailer or platform launching a german current account or card product without applying for its own licence and a fintech that needs deposit taking and lending, which an e-money licence cannot provide are not what Stainless is typically brought in for.
What can Solaris do that Stainless cannot?
Solaris covers German banking licence, IBAN accounts, Card issuing, Lending as a service. Stainless covers SDK generation, MCP server generation, Docs site generation, Webhooks and streaming support.

Answered from the vendors’ own pages

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.

Stainless: Is there a free plan, and what are its limits?

Yes. The Free plan supports up to 5 generators, 5 seats, APIs with 25 or fewer endpoints, and 100 preview builds per month, with email support.

Source
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.

Stainless: Who owns the generated SDK code?

The generated SDK code is owned by the customer and published by Stainless under the Apache 2.0 license.

Source
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.

Stainless: What happens if I exceed my plan's endpoint limit?

Customers exceeding their endpoint limits are billed per SDK, per endpoint, per month for the overage.

Source
Share

Related pages

More on Solaris

More on Stainless

Keep looking

Other head to heads