Specification and tools for defining asynchronous APIs
As of 30 August 2026, Asyncapi is free to use. AsyncAPI is an open-source specification and tools for defining asynchronous APIs. Softwr lists it under APIs. Asyncapi is launched in 2016, available on Web, API.
Overview
AsyncAPI is an open-source specification and tools for defining asynchronous APIs. It extends OpenAPI concepts to event-driven and real-time APIs, providing documentation and code generation for message-based systems.
The honest half
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Cross-shopped
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Swagger/OpenAPI: OpenAPI is the established specification for REST APIs, while AsyncAPI covers event-driven async systems. Both are complementary API specification standards hosted by the Linux Foundation.
Hasura: Hasura provides event-driven capabilities with subscriptions and webhooks, supporting real-time event consumption similar to AsyncAPI's scope.
Pricing
Taken from the vendor's own pricing page. Prices move, so check before you buy.
Open Source
Free
Capabilities
API Specification
Code generation
Documentation
Multiple messaging protocols
Integration with Multiple messaging protocols
Code generators
Integration with Code generators
Specification support
Available on Specification
Tools support
Available on Tools
CLI support
Available on CLI
Answered, with sources
Each answer names the page it came from, so you can check it rather than take our word for it.
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.
SourceYes, 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.
SourceAsyncAPI 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.
SourceYes, AsyncAPI has IDE extensions available for VSCode and IntelliJ, along with CLI utilities and GitHub Actions integration for developers.
SourceBehind it
Timeline
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