openapi: 3.0.1
info:
  title: Plunk Campaigns Transactional API
  description: 'The Plunk REST API for the open-source email platform for SaaS. Plunk unifies transactional email (send), event tracking for automations (track), contact / subscriber management, and marketing campaigns behind a single Bearer-authenticated API. Public API routes under /v1 return a wrapped envelope ({"success": true, "data": ...}); most routes require a secret key (sk_), while /v1/track may also be called with a public key (pk_) for client-side use. The same API is served by the hosted platform and by self-hosted (AGPL-3.0) deployments.'
  termsOfService: https://www.useplunk.com/legal/terms
  contact:
    name: Plunk Support
    url: https://docs.useplunk.com
  license:
    name: AGPL-3.0
    url: https://github.com/useplunk/plunk/blob/main/LICENSE
  version: '1.0'
servers:
- url: https://api.useplunk.com/v1
  description: Plunk hosted API
security:
- bearerAuth: []
tags:
- name: Transactional
  description: Send transactional email.
paths:
  /send:
    post:
      operationId: sendEmail
      tags:
      - Transactional
      summary: Send a transactional email
      description: Sends a single transactional email to one or more recipients using a secret API key. The body may be HTML or plain text. Optional fields allow overriding the sender, reply-to, custom headers, and attachments.
      security:
      - bearerAuth: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/SendEmailRequest'
            example:
              to: user@example.com
              subject: Welcome to our app
              body: <p>Thanks for signing up!</p>
      responses:
        '200':
          description: Email accepted for delivery.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SendEmailResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/ValidationError'
        '429':
          $ref: '#/components/responses/RateLimited'
components:
  schemas:
    SendEmailResponse:
      type: object
      properties:
        success:
          type: boolean
        emails:
          type: array
          items:
            type: object
            properties:
              contact:
                type: object
                properties:
                  id:
                    type: string
                  email:
                    type: string
              email:
                type: string
        timestamp:
          type: string
          format: date-time
    Error:
      type: object
      properties:
        success:
          type: boolean
          example: false
        code:
          type: integer
        error:
          type: string
        message:
          type: string
        time:
          type: integer
    SendEmailRequest:
      type: object
      required:
      - to
      - subject
      - body
      properties:
        to:
          description: Recipient email address, or an array of addresses.
          oneOf:
          - type: string
            format: email
          - type: array
            items:
              type: string
              format: email
        subject:
          type: string
          description: Email subject line.
        body:
          type: string
          description: Email body, as HTML or plain text.
        subscribed:
          type: boolean
          description: Whether the recipient is treated as a subscribed contact.
        name:
          type: string
          description: Display name to send from.
        from:
          type: string
          format: email
          description: Sender email address (must be a verified sender).
        reply:
          type: string
          format: email
          description: Reply-to email address.
        headers:
          type: object
          additionalProperties:
            type: string
          description: Custom email headers.
        attachments:
          type: array
          description: File attachments.
          items:
            type: object
            properties:
              filename:
                type: string
              content:
                type: string
                description: Base64-encoded file content.
              type:
                type: string
                description: MIME type of the attachment.
  responses:
    ValidationError:
      description: The request body failed validation.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: Missing or invalid API key.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    RateLimited:
      description: Too many requests; the project rate limit was exceeded.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: Plunk API key passed as a Bearer token. Use a secret key (sk_) for most endpoints; the /track endpoint additionally accepts a public key (pk_).