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APIs · head to head

Asyncapi vs Cucumber

Asyncapi logo

Asyncapi

APIs

Specification and tools for defining asynchronous APIs

From
Free
Rated
-
Full reviewWebsite
Cucumber logo

Cucumber

Testing

Behaviour-driven development testing framework that returned to community ownership after nine years under SmartBear

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Asyncapi complex to implement and debug asynchronous operations due to their non-linear and concurrent nature; Cucumber gherkin's plain-language layer adds a real maintenance burden, keeping feature files, step definitions and implementation code synchronised across a large suite is a known source of drift and duplicated effort.
  • They diverge on capability: Asyncapi covers API Specification, Cucumber covers Gherkin syntax.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Asyncapi and Cucumber actually diverge.

Attributes where Asyncapi and Cucumber differ
AttributeAsyncapiCucumber
Pricing modelopen-sourceOpen source, no licence fee
PlatformsWeb, CLI, IDE ExtensionsLinux, macOS, Windows
CategoryAPIsTesting
Founded2019Unknown

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 Asyncapi

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

Only in Cucumber

  • Gherkin syntax
  • Step definition binding
  • Multi-language support
  • Living documentation
  • Tagging and scenario outlines
  • Reporting plugins

What people use each for

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

Asyncapi

  • API Developmentnot Cucumber
  • API Gatewaynot Cucumber
  • API Testingnot Cucumber
  • API Documentationnot Cucumber
  • Microservicesnot Cucumber

Cucumber

  • A team practising behaviour-driven development that wants shared, readable specifications between product owners and engineersnot Asyncapi
  • An organisation wanting living documentation that stays synchronised with actual test coverage rather than a separate specification documentnot Asyncapi
  • A QA team migrating acceptance tests from a proprietary BDD tool to an open source, community-governed alternativenot Asyncapi
  • A Java, JavaScript or Ruby project needing a mature BDD framework rather than building Gherkin-style parsing from scratchnot 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

Cucumber

  • Gherkin's plain-language layer adds a real maintenance burden, keeping feature files, step definitions and implementation code synchronised across a large suite is a known source of drift and duplicated effort.
  • Ownership has moved twice in under a decade, from independent to SmartBear-owned to independent community ownership again, which should temper confidence in any specific long-range roadmap claim.
  • Non-technical stakeholders who are meant to read and write Gherkin scenarios often do not engage with them in practice, leaving the readability benefit unrealised while the maintenance cost remains.
  • Step definition reuse across a large feature file set can become tangled, with ambiguous step matching causing hard-to-debug failures as a suite grows.
  • As a community-owned project without a corporate backer's support infrastructure, enterprise buyers wanting a formal support contract have no vendor to buy one from, unlike some competing BDD tools still sold commercially.

Pricing, plan by plan

Asyncapi

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

Cucumber

Free
  • CucumberFree
    • Full functionality across Cucumber-JVM, Cucumber-JS, Cucumber-Ruby and other implementations
    • Community support via GitHub
    • Returned to independent community ownership in December 2024 after nine years connected to SmartBear

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 Cucumber if

  • You need gherkin syntax.
  • You want to start without paying.
  • You work on Linux, macOS, Windows.
  • You also want step definition binding.
Cucumber review

Questions people ask

Is Asyncapi or Cucumber better?
Neither clearly leads. Asyncapi starts at Free and Cucumber at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Asyncapi or Cucumber?
Asyncapi starts at Free and Cucumber at Free.
Does Asyncapi or Cucumber run on more platforms?
Asyncapi runs on Web, CLI, IDE Extensions. Cucumber runs on Linux, macOS, Windows.
Can I use Asyncapi for free?
Both have a free tier, so you can try either at no cost before committing.
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 Cucumber is typically brought in for.
What can Asyncapi do that Cucumber cannot?
Asyncapi covers API Specification, Code generation, Documentation, Multiple messaging protocols. Cucumber covers Gherkin syntax, Step definition binding, Multi-language support, Living documentation.

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
Cucumber: Is Cucumber owned by SmartBear?

No, not currently. SmartBear acquired Cucumber Ltd in 2019 but the open source project returned to independent community ownership in December 2024.

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
Cucumber: Is Cucumber free?

Yes, entirely open source with no licence fee across all its language implementations.

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
Cucumber: Does Cucumber replace Selenium or Appium?

No, Cucumber provides the Gherkin specification layer and step definition binding; the actual browser or mobile automation still needs a driver such as Selenium or Appium underneath.

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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