openapi: 3.0.1
info:
  title: Customer.io Broadcasts Transactional API
  description: Specification of the Customer.io APIs for customer messaging and marketing automation. Covers the Track API (track.customer.io - people, events, devices, manual segments, plus the v2 entity/batch endpoints), the App / Transactional API (api.customer.io - transactional send, API-triggered broadcasts, customers, segments, campaigns, newsletters, messages, exports, collections, snippets, sender identities, imports), and the Pipelines / Data Pipelines CDP API (cdp.customer.io - identify, track, page, screen, group, alias, batch). Authentication differs per surface - the Track API uses HTTP Basic auth with site_id:api_key, the App and Pipelines APIs use a Bearer token.
  termsOfService: https://customer.io/legal/terms-of-service/
  contact:
    name: Customer.io Support
    email: win@customer.io
  version: '1.0'
servers:
- url: https://track.customer.io
  description: Track API (US region)
- url: https://track-eu.customer.io
  description: Track API (EU region)
- url: https://api.customer.io
  description: App / Transactional API (US region)
- url: https://api-eu.customer.io
  description: App / Transactional API (EU region)
- url: https://cdp.customer.io
  description: Pipelines / Data Pipelines CDP API (US region)
- url: https://cdp-eu.customer.io
  description: Pipelines / Data Pipelines CDP API (EU region)
security:
- basicAuth: []
- bearerAuth: []
tags:
- name: Transactional
  description: App API - send transactional email, push, SMS, and in-app messages.
paths:
  /v1/send/email:
    post:
      operationId: sendTransactionalEmail
      tags:
      - Transactional
      summary: Send a transactional email
      description: Send a single transactional email using a transactional message template or inline body. App API Bearer token required.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SendEmailRequest'
      responses:
        '200':
          description: Message accepted for delivery.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SendResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
      security:
      - bearerAuth: []
  /v1/send/push:
    post:
      operationId: sendTransactionalPush
      tags:
      - Transactional
      summary: Send a transactional push notification
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SendPushRequest'
      responses:
        '200':
          description: Push accepted for delivery.
        '401':
          $ref: '#/components/responses/Unauthorized'
      security:
      - bearerAuth: []
  /v1/send/sms:
    post:
      operationId: sendTransactionalSms
      tags:
      - Transactional
      summary: Send a transactional SMS
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                transactional_message_id:
                  oneOf:
                  - type: string
                  - type: integer
                to:
                  type: string
                identifiers:
                  $ref: '#/components/schemas/Identifiers'
                message_data:
                  type: object
                  additionalProperties: true
      responses:
        '200':
          description: SMS accepted for delivery.
        '401':
          $ref: '#/components/responses/Unauthorized'
      security:
      - bearerAuth: []
components:
  schemas:
    Identifiers:
      type: object
      description: One or more identifiers locating a person (id, email, or cio_id).
      properties:
        id:
          type: string
        email:
          type: string
        cio_id:
          type: string
    SendEmailRequest:
      type: object
      properties:
        transactional_message_id:
          oneOf:
          - type: string
          - type: integer
          description: ID or trigger name of a transactional message template.
        to:
          type: string
        identifiers:
          $ref: '#/components/schemas/Identifiers'
        from:
          type: string
        subject:
          type: string
        body:
          type: string
        message_data:
          type: object
          additionalProperties: true
        attachments:
          type: object
          additionalProperties:
            type: string
        disable_message_retention:
          type: boolean
        send_to_unsubscribed:
          type: boolean
    SendPushRequest:
      type: object
      properties:
        transactional_message_id:
          oneOf:
          - type: string
          - type: integer
        to:
          type: string
        identifiers:
          $ref: '#/components/schemas/Identifiers'
        title:
          type: string
        message:
          type: string
        message_data:
          type: object
          additionalProperties: true
    Error:
      type: object
      properties:
        meta:
          type: object
          properties:
            error:
              type: string
            errors:
              type: array
              items:
                type: string
    SendResponse:
      type: object
      properties:
        delivery_id:
          type: string
        queued_at:
          type: integer
        recipient:
          type: object
          additionalProperties: true
  responses:
    Unauthorized:
      description: Authentication failed or credentials missing.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    basicAuth:
      type: http
      scheme: basic
      description: Track API auth. Base-64 encode site_id:api_key and pass it in the Authorization header (Basic ...).
    bearerAuth:
      type: http
      scheme: bearer
      description: App API and Pipelines API auth. Pass the App API key (or Pipelines source write key) as a Bearer token in the Authorization header.