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APIs · head to head

Asyncapi vs Solaris

Asyncapi logo

Asyncapi

APIs

Specification and tools for defining asynchronous APIs

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 Asyncapi has a free tier, so it costs nothing to try first.
  • Each has a real cost: Asyncapi complex to implement and debug asynchronous operations due to their non-linear and concurrent nature; 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: Asyncapi covers API Specification, Solaris covers German banking licence.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Asyncapi and Solaris actually diverge.

Attributes where Asyncapi and Solaris differ
AttributeAsyncapiSolaris
Starting priceFreeOn request
Pricing modelopen-sourcequote
Free tierYesNo
PlatformsWeb, CLI, IDE ExtensionsWeb, API
Founded2019Unknown

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 Asyncapi

  • API Specification
  • Code generation
  • Documentation
  • Multiple messaging protocols
  • Code generators
  • Specification support
  • Tools support
  • CLI support

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.

Asyncapi

  • API Developmentnot Solaris
  • API Gatewaynot Solaris
  • API Testingnot Solaris
  • API Documentationnot Solaris
  • Microservicesnot Solaris

Solaris

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

Where each one falls short

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

Asyncapi

  • Complex to implement and debug asynchronous operations due to their non-linear and concurrent nature
  • Keeping AsyncAPI documents up to date is challenging as systems evolve
  • Tracing and debugging asynchronous operations is more difficult than synchronous request-response patterns

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

Asyncapi

Free
  • Open SourceFree
    • AsyncAPI specification
    • Tools
    • Community support

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 Asyncapi if

  • You need api specification.
  • You want to start without paying.
  • You work on Web, CLI, IDE Extensions.
  • You also want code generation.
Asyncapi 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 Asyncapi or Solaris better?
Neither clearly leads. Asyncapi 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, Asyncapi or Solaris?
Asyncapi has a free tier; the other does not. Paid plans start at Free for Asyncapi and On request for Solaris.
Does Asyncapi or Solaris run on more platforms?
Asyncapi runs on Web, CLI, IDE Extensions. Solaris runs on Web, API.
Can I use Asyncapi for free?
Yes. Asyncapi has a free tier, so you can try it without paying. Solaris starts at On request.
What is Asyncapi best used for?
Asyncapi is most often used for api development, api gateway, api testing, api documentation. Of those, api development and api gateway are not what Solaris is typically brought in for.
What can Asyncapi do that Solaris cannot?
Asyncapi covers API Specification, Code generation, Documentation, Multiple messaging protocols. Solaris covers German banking licence, IBAN accounts, Card issuing, Lending as a service.

Answered from the vendors’ own pages

Asyncapi: What is AsyncAPI used for?

AsyncAPI is an open-source specification for defining and documenting asynchronous APIs, message-driven systems, and event-driven architectures. It serves the same purpose for async APIs as OpenAPI does for REST APIs, providing standardized documentation, code generation, and tooling.

Source
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.

Asyncapi: Is AsyncAPI free to use?

Yes, AsyncAPI is completely free and open-source. It is hosted by the Linux Foundation and supported by community contributions and sponsorships from companies like Postman, IBM, IQVIA Technology, and Solace.

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.

Asyncapi: What protocols and technologies does AsyncAPI support?

AsyncAPI supports multiple protocols and technologies including Kafka, RabbitMQ, MQTT, Socket.IO, AWS EventBridge, and others. It provides language support for JavaScript/TypeScript, Python, Java, Go, C#/.NET, Kotlin, and PHP.

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.

Asyncapi: Does AsyncAPI have IDE support?

Yes, AsyncAPI has IDE extensions available for VSCode and IntelliJ, along with CLI utilities and GitHub Actions integration for developers.

Source
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