AsyncAPI · Schema

AsyncAPI Message

An AsyncAPI Message — describes the data flowing over a channel: headers, payload, content type, correlation id, examples, and protocol-specific message bindings.

AsyncAPIEvent-Driven ArchitectureAsynchronous APIsMessage BrokersAPI SpecificationsKafkaMQTTAMQPWebSocketLinux Foundation

Properties

Name	Type	Description
messageId	string	Unique identifier for the message inside the document. Required when referenced from outside an inline definition.
name	string	Machine-friendly name of the message. Used in code generation.
title	string	Human-readable title.
summary	string
description	string
contentType	string	MIME type of the payload. Overrides defaultContentType.
schemaFormat	string	Schema format identifier for the payload. Defaults to AsyncAPI's own subset of JSON Schema.
headers	object	Schema describing the message headers (Kafka headers, AMQP properties, MQTT user properties).
payload	object	Schema describing the message payload. Format determined by schemaFormat.
correlationId	object	Correlation ID definition — a JSONPath/runtime expression pointing to a value in the message used to correlate request and reply.
tags	array
externalDocs	object
bindings	object	Protocol-specific message bindings (kafka key, mqtt retain, amqp delivery mode, etc.).
examples	array	Array of example message values for documentation, mocking, and contract testing.
traits	array	List of message traits merged into the message.

View JSON Schema on GitHub

JSON Schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://raw.githubusercontent.com/api-evangelist/async-apis/refs/heads/main/json-schema/asyncapi-message-schema.json",
  "title": "AsyncAPI Message",
  "description": "An AsyncAPI Message — describes the data flowing over a channel: headers, payload, content type, correlation id, examples, and protocol-specific message bindings.",
  "type": "object",
  "properties": {
    "messageId": {
      "type": "string",
      "description": "Unique identifier for the message inside the document. Required when referenced from outside an inline definition."
    },
    "name": {
      "type": "string",
      "description": "Machine-friendly name of the message. Used in code generation."
    },
    "title": {
      "type": "string",
      "description": "Human-readable title."
    },
    "summary": {
      "type": "string"
    },
    "description": {
      "type": "string"
    },
    "contentType": {
      "type": "string",
      "description": "MIME type of the payload. Overrides defaultContentType.",
      "examples": ["application/json", "application/cloudevents+json", "application/avro", "application/protobuf"]
    },
    "schemaFormat": {
      "type": "string",
      "description": "Schema format identifier for the payload. Defaults to AsyncAPI's own subset of JSON Schema.",
      "examples": [
        "application/vnd.aai.asyncapi+json;version=3.0.0",
        "application/schema+json;version=draft-07",
        "application/vnd.apache.avro;version=1.9.0",
        "application/vnd.google.protobuf;version=3"
      ]
    },
    "headers": {
      "type": "object",
      "description": "Schema describing the message headers (Kafka headers, AMQP properties, MQTT user properties)."
    },
    "payload": {
      "description": "Schema describing the message payload. Format determined by schemaFormat."
    },
    "correlationId": {
      "type": "object",
      "description": "Correlation ID definition — a JSONPath/runtime expression pointing to a value in the message used to correlate request and reply."
    },
    "tags": {
      "type": "array",
      "items": {"type": "object"}
    },
    "externalDocs": {
      "type": "object"
    },
    "bindings": {
      "type": "object",
      "description": "Protocol-specific message bindings (kafka key, mqtt retain, amqp delivery mode, etc.).",
      "properties": {
        "kafka": {"type": "object"},
        "mqtt": {"type": "object"},
        "amqp": {"type": "object"},
        "ws": {"type": "object"},
        "http": {"type": "object"},
        "jms": {"type": "object"}
      }
    },
    "examples": {
      "type": "array",
      "description": "Array of example message values for documentation, mocking, and contract testing.",
      "items": {
        "type": "object",
        "properties": {
          "name": {"type": "string"},
          "summary": {"type": "string"},
          "headers": {"type": "object"},
          "payload": {}
        }
      }
    },
    "traits": {
      "type": "array",
      "description": "List of message traits merged into the message.",
      "items": {"type": "object"}
    }
  }
}