Midjourney Image Generation Webhooks

asyncapi: 2.6.0
info:
  title: Midjourney Image Generation Webhooks
  description: >-
    The Midjourney Image Generation webhook interface delivers real-time
    notifications about image generation job status changes. When a webhook
    URL is provided during job creation, Midjourney sends HTTP POST requests
    to the specified URL whenever a job transitions between states such as
    pending, in progress, completed, or failed. This eliminates the need
    for polling the job status endpoint and enables event-driven integration
    patterns for applications consuming Midjourney's image generation
    capabilities.
  version: '1.0.0'
  contact:
    name: Midjourney Support
    url: https://docs.midjourney.com/hc/en-us
servers:
  webhookReceiver:
    url: '{webhookUrl}'
    protocol: https
    description: >-
      The webhook receiver endpoint configured by the client application.
      Midjourney sends HTTP POST requests to this URL when job status
      changes occur. The URL is specified per-job in the webhook_url
      parameter of generation requests.
    variables:
      webhookUrl:
        description: >-
          The client-provided webhook URL that receives job status
          notifications.
    security:
      - webhookSignature: []
channels:
  /webhook:
    description: >-
      Webhook delivery channel for image generation job status events.
      Events are sent as HTTP POST requests with a JSON payload containing
      the full job object. The webhook_type parameter specified during job
      creation controls whether progress updates or only final results
      are delivered.
    publish:
      operationId: receiveJobStatusEvent
      summary: Receive job status change notifications
      description: >-
        Receives webhook notifications when an image generation job changes
        status. The payload includes the complete job object with current
        status, progress percentage, and result data when available. Events
        are delivered for status transitions including pending to in_progress,
        in_progress progress updates, and terminal states such as completed,
        failed, or cancelled.
      message:
        oneOf:
          - $ref: '#/components/messages/JobProgressEvent'
          - $ref: '#/components/messages/JobCompletedEvent'
          - $ref: '#/components/messages/JobFailedEvent'
          - $ref: '#/components/messages/JobCancelledEvent'
components:
  securitySchemes:
    webhookSignature:
      type: httpApiKey
      name: X-Midjourney-Signature
      in: header
      description: >-
        HMAC-SHA256 signature of the webhook payload for verifying that
        the notification originated from Midjourney. The signature is
        computed using the webhook secret associated with the API key.
        Clients should validate this signature before processing the
        webhook payload to prevent spoofed notifications.
  messages:
    JobProgressEvent:
      name: jobProgress
      title: Job Progress Event
      summary: >-
        Sent when a job's progress percentage updates during processing.
        Only delivered when webhook_type is set to progress.
      contentType: application/json
      payload:
        $ref: '#/components/schemas/JobWebhookPayload'
    JobCompletedEvent:
      name: jobCompleted
      title: Job Completed Event
      summary: >-
        Sent when a job finishes successfully and generated images are
        available for download. The result field contains URLs of all
        generated images.
      contentType: application/json
      payload:
        $ref: '#/components/schemas/JobWebhookPayload'
    JobFailedEvent:
      name: jobFailed
      title: Job Failed Event
      summary: >-
        Sent when a job fails due to an error such as content policy
        violation, invalid parameters, or an internal processing error.
        The error field contains details about the failure.
      contentType: application/json
      payload:
        $ref: '#/components/schemas/JobWebhookPayload'
    JobCancelledEvent:
      name: jobCancelled
      title: Job Cancelled Event
      summary: >-
        Sent when a job is cancelled by the user before completion.
      contentType: application/json
      payload:
        $ref: '#/components/schemas/JobWebhookPayload'
  schemas:
    JobWebhookPayload:
      type: object
      description: >-
        The webhook payload delivered for job status change events.
        Contains the complete job object with current state and results.
      required:
        - event
        - job_id
        - status
        - timestamp
      properties:
        event:
          type: string
          description: >-
            The type of webhook event being delivered.
          enum:
            - job.progress
            - job.completed
            - job.failed
            - job.cancelled
        job_id:
          type: string
          format: uuid
          description: >-
            The unique identifier of the job that triggered this event.
        status:
          type: string
          description: >-
            The current status of the job.
          enum:
            - pending
            - in_progress
            - completed
            - failed
            - cancelled
        progress:
          type: integer
          description: >-
            The completion progress as a percentage from 0 to 100.
          minimum: 0
          maximum: 100
        type:
          type: string
          description: >-
            The type of image generation operation.
          enum:
            - imagine
            - upscale
            - variation
            - describe
            - blend
        prompt:
          type: string
          description: >-
            The text prompt used for the generation job.
        result:
          type: object
          description: >-
            The generation results, present when the job has completed
            successfully.
          properties:
            images:
              type: array
              description: >-
                List of generated image URLs and metadata.
              items:
                type: object
                properties:
                  url:
                    type: string
                    format: uri
                    description: >-
                      The download URL for the generated image.
                  index:
                    type: integer
                    description: >-
                      The position of this image in the generation grid.
                  width:
                    type: integer
                    description: >-
                      The width of the image in pixels.
                  height:
                    type: integer
                    description: >-
                      The height of the image in pixels.
            prompts:
              type: array
              description: >-
                Generated prompt suggestions for describe jobs.
              items:
                type: string
        error:
          type: object
          description: >-
            Error details, present when the job has failed.
          properties:
            code:
              type: string
              description: >-
                Machine-readable error code.
            message:
              type: string
              description: >-
                Human-readable error description.
        timestamp:
          type: string
          format: date-time
          description: >-
            ISO 8601 timestamp when this webhook event was generated.