> Markdown version of https://www.asyncapi.com/docs/tutorials/getting-started/asyncapi-documents
> Index: https://www.asyncapi.com/llms.txt

# AsyncAPI documents

An AsyncAPI document is a file that defines and annotates the different components of **a specific Event-Driven API**.

The file format must be JSON or YAML; however, only the subset of YAML that matches the JSON capabilities is allowed.

```yaml
asyncapi: 3.1.0
info:
  title: Example application
  version: '0.1.0'
channels:
  userSignup:
    address: 'user/signedup'
    messages:
      userSignedupMessage: 
        description: A message describing that a user just signed up.
        payload:
          type: object
          additionalProperties: false
          properties:
            fullName:
              type: string
            email:
              type: string
              format: email
            age:
              type: integer
              minimum: 18
operations:
  publishUserSignedup:
    action: 'send'
    channel:
      $ref: '#/channels/userSignup'
```

The AsyncAPI document is a machine-readable definition of your Event-Driven API. That document can be used afterward to generate documentation and code, validate the messages that `Example application` sends, and even apply API management policies to your messages before they arrive at the broker.

Your API documentation is now machine-readable (easily parseable by code) so the myriad of useful applications is endless.