openapi: 3.1.0
info:
  title: Customer.io App Activities Messages API
  description: The Customer.io App API enables developers to manage workspace resources and send messages programmatically. It provides endpoints for sending transactional messages, triggering broadcasts, managing customers and segments, retrieving campaign and newsletter data, and exporting customer information. The API uses bearer token authentication with an App API key and is designed for operations that go beyond data ingestion, such as retrieving metrics, managing message templates, and automating outbound communications from Customer.io.
  version: 1.0.0
  contact:
    name: Customer.io Support
    url: https://customer.io/contact
  termsOfService: https://customer.io/legal/terms-of-service
servers:
- url: https://api.customer.io/v1
  description: US Production Server
- url: https://api-eu.customer.io/v1
  description: EU Production Server
security:
- bearerAuth: []
tags:
- name: Messages
  description: Retrieve information about individual messages sent to customers.
paths:
  /messages/{message_id}:
    get:
      operationId: getMessage
      summary: Get a message
      description: Returns detailed information about a specific message that was sent, including delivery status and engagement metrics.
      tags:
      - Messages
      parameters:
      - $ref: '#/components/parameters/MessageId'
      responses:
        '200':
          description: Message details.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Message'
        '401':
          description: Unauthorized. Invalid App API key.
        '404':
          description: Message not found.
components:
  schemas:
    Message:
      type: object
      description: A message that was sent to a customer.
      properties:
        id:
          type: string
          description: The unique message identifier.
        type:
          type: string
          description: The message type (email, push, sms, webhook, in-app).
        subject:
          type: string
          description: The message subject line.
        customer_id:
          type: string
          description: The recipient customer identifier.
        campaign_id:
          type: integer
          description: The associated campaign identifier.
        created:
          type: integer
          description: UNIX timestamp of when the message was created.
        metrics:
          type: object
          description: Message delivery and engagement metrics.
          properties:
            sent:
              type: integer
              description: UNIX timestamp of when the message was sent.
            delivered:
              type: integer
              description: UNIX timestamp of when the message was delivered.
            opened:
              type: integer
              description: UNIX timestamp of when the message was opened.
            clicked:
              type: integer
              description: UNIX timestamp of when a link was clicked.
            bounced:
              type: integer
              description: UNIX timestamp of when the message bounced.
  parameters:
    MessageId:
      name: message_id
      in: path
      required: true
      description: The unique identifier for the message.
      schema:
        type: string
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: Bearer token authentication using your App API key. Pass the key in the Authorization header as Bearer {app_api_key}.
externalDocs:
  description: App API Documentation
  url: https://docs.customer.io/integrations/api/app/