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APIs · head to head

Asyncapi vs Thunder Client

Asyncapi logo

Asyncapi

APIs

Specification and tools for defining asynchronous APIs

From
Free
Rated
-
Full reviewWebsite
Thunder Client logo

Thunder Client

APIs

Lightweight REST API client built as VSCode extension

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; Thunder Client paid plans are billed annually only: Starter is $3 per user per month and capped at a maximum of 10 seats, Business is $7 per user per month with 500 monthly collection runs per user, and Enterprise is $16 per user per month for unlimited runs
  • They diverge on capability: Asyncapi covers API Specification, Thunder Client covers REST Client.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Asyncapi and Thunder Client actually diverge.

Attributes where Asyncapi and Thunder Client differ
AttributeAsyncapiThunder Client
Pricing modelopen-sourcefreemium
PlatformsWeb, CLI, IDE ExtensionsVSCode extension, Web
Founded20192021

Identical on both: starting price (Free), free tier (Yes), 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 Thunder Client

  • REST Client
  • Environment variables
  • Response testing
  • VSCode
  • GitHub
  • Webhook support
  • VSCode extension support
  • Web support

What people use each for

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

Asyncapi

  • API Development
  • API Gateway
  • API Testing
  • API Documentation
  • Microservices

Thunder Client

  • API Development
  • API Gateway
  • API Testing
  • API Documentation
  • Microservices

Both are used for api development, api gateway, api testing, api documentation, microservices, on those jobs the choice comes down to price and fit rather than capability.

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

Thunder Client

  • Paid plans are billed annually only: Starter is $3 per user per month and capped at a maximum of 10 seats, Business is $7 per user per month with 500 monthly collection runs per user, and Enterprise is $16 per user per month for unlimited runs

Pricing, plan by plan

Asyncapi

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

Thunder Client

Free
  • FreeFree
    • REST client
    • Collection management
    • Local testing
  • Pro$8/monthly
    • Cloud sync
    • Team collaboration
    • Advanced features

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 Thunder Client if

  • You need rest client.
  • You want to start without paying.
  • You work on VSCode extension, Web.
  • You also want environment variables.
Thunder Client review

Questions people ask

Is Asyncapi or Thunder Client better?
Neither clearly leads. Asyncapi starts at Free and Thunder Client at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Asyncapi or Thunder Client?
Asyncapi starts at Free and Thunder Client at Free.
Does Asyncapi or Thunder Client run on more platforms?
Asyncapi runs on Web, CLI, IDE Extensions. Thunder Client runs on VSCode extension, Web.
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.
What can Asyncapi do that Thunder Client cannot?
Asyncapi covers API Specification, Code generation, Documentation, Multiple messaging protocols. Thunder Client covers REST Client, Environment variables, Response testing, VSCode.

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
Thunder Client: How much does Thunder Client cost?

Thunder Client publishes a free plan at no cost, then Starter at $3, Business at $7 and Enterprise at $16, all priced annually.

Source
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
Thunder Client: Is Thunder Client free?

Yes, there is a free plan. It is used through the Thunder Client extension for VS Code, available from the marketplace, with limits applied compared with the paid tiers.

Source
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
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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