> ## Documentation Index > Fetch the complete documentation index at: https://devs.izap.ai/llms.txt > Use this file to discover all available pages before exploring further. # Preview a transmission > Validates the recipient list and template and stores the result as a draft, without sending anything. Review the draft, then confirm it to dispatch. ## OpenAPI ````yaml /api-reference/openapi.json post /api/v1/transmissions/preview openapi: 3.1.0 info: contact: email: suporte@izap.ai name: iZap API Support description: Public REST API for the iZap WhatsApp business messaging platform. license: name: MIT url: https://opensource.org/licenses/MIT title: iZap API version: v1 servers: - description: Production url: https://api.izap.ai - description: Staging url: https://api-staging.izap.ai security: [] tags: - description: >- Personal access tokens for calling this API, plus introspection of the token presented on a request. name: api-tokens - description: >- Create a business, read and update its profile, and manage its opening hours. name: businesses - description: >- Reusable images belonging to the caller's business, referenced when composing messages. name: business-library - description: Product catalog menus a business publishes to its customers. name: menus - description: >- Provision and inspect the WhatsApp Cloud API numbers attached to a business: registration, WABA details, per-number assistant binding and catalog sends. name: whatsapp-cloud - description: >- Conversation lifecycle — list, create and delete chats, and control read, snooze, status and AI pause state. name: chats - description: >- Read a conversation's messages, send free-form or template replies, and upload attachments. name: messages - description: >- Manage WhatsApp message templates: draft them locally, submit them to Meta for review and sync approval status back. name: whatsapp-templates - description: >- Bulk template sends. A transmission is previewed into a draft, then confirmed or cancelled — confirming dispatches to real recipients. name: transmissions - description: >- Register URLs that receive signed event deliveries when something happens in a business, rotate their signing secrets, and replay an individual delivery. name: webhooks - description: >- Server-rendered order visualisation page for a business slug, behind HTTP Basic auth. name: orders paths: /api/v1/transmissions/preview: post: tags: - transmissions summary: Preview a transmission description: >- Validates the recipient list and template and stores the result as a draft, without sending anything. Review the draft, then confirm it to dispatch. operationId: previewTransmission parameters: - in: header name: business-id required: true schema: format: uuid title: Business-Id type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/CreateTransmissionPreviewIn' required: true responses: '200': content: application/json: schema: $ref: '#/components/schemas/TransmissionPreviewOut' description: Successful Response '401': content: application/json: schema: $ref: '#/components/schemas/ApiError' description: Missing or invalid credentials. '403': content: application/json: schema: $ref: '#/components/schemas/ApiError' description: The credential is valid but not authorized for this action. '404': content: application/json: schema: $ref: '#/components/schemas/ApiError' description: The resource, or the business named in the request, does not exist. '422': content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' description: Validation Error default: content: application/json: schema: $ref: '#/components/schemas/ApiError' description: Unexpected error. security: - bearerAuth: [] components: schemas: CreateTransmissionPreviewIn: description: >- Validate CSV recipients against a template and create a DRAFT transmission. No messages are sent. ``recipients`` are parsed CSV rows (header -> value); each row must contain ``phone_column`` and the columns that fill the template's variables. Confirm the returned draft id with ``confirm_transmission`` to send. properties: business_id: anyOf: - format: uuid type: string - type: 'null' title: Business Id max_messages_per_minute: default: 60 description: Sending pace cap. Must be between 1 and 200 messages per minute. maximum: 200 minimum: 1 title: Max Messages Per Minute type: integer name: description: Human label for the transmission. maxLength: 255 minLength: 1 title: Name type: string phone_column: default: phone description: >- Name of the CSV column holding the recipient phone number (E.164 or local). maxLength: 255 minLength: 1 title: Phone Column type: string recipients: description: >- Parsed CSV rows; each row maps a string column header to its string cell value. Must include the phone column and the columns that supply the template's variables. items: additionalProperties: type: string type: object maxItems: 5000 minItems: 1 title: Recipients type: array scheduled_at: anyOf: - format: date-time type: string - type: 'null' description: >- When to send. Omit or null to send immediately on confirm. If the value has no timezone offset it is interpreted in 'timezone'. title: Scheduled At template_language: default: pt_BR description: Template language/locale code as registered with Meta, e.g. 'pt_BR'. maxLength: 15 minLength: 2 title: Template Language type: string template_name: description: Name of the pre-approved WhatsApp Cloud API template to send. maxLength: 512 minLength: 1 title: Template Name type: string timezone: default: America/Sao_Paulo description: IANA timezone used to interpret a naive 'scheduled_at'. title: Timezone type: string transmission_type: const: whatsapp_template default: whatsapp_template description: Only 'whatsapp_template' is supported for now. title: Transmission Type type: string variable_columns: anyOf: - items: type: string maxItems: 50 type: array - type: 'null' description: >- For positional templates ({{1}}, {{2}}, ...): the ordered CSV header names mapping to {{1}}, {{2}}, ... If omitted, the first non-phone columns are used in order. Ignored for templates with named placeholders. title: Variable Columns required: - name - template_name - recipients title: CreateTransmissionPreviewIn type: object TransmissionPreviewOut: properties: business_id: format: uuid title: Business Id type: string column_mapping: additionalProperties: type: string title: Column Mapping type: object duplicate_count: title: Duplicate Count type: integer estimated_duration_seconds: title: Estimated Duration Seconds type: integer invalid_count: title: Invalid Count type: integer name: title: Name type: string not_on_whatsapp_count: default: 0 title: Not On Whatsapp Count type: integer phone_column: title: Phone Column type: string recipient_count: title: Recipient Count type: integer sample_errors: items: $ref: '#/components/schemas/PreviewRowErrorOut' title: Sample Errors type: array scheduled_at: anyOf: - format: date-time type: string - type: 'null' title: Scheduled At status: title: Status type: string template_language: title: Template Language type: string template_name: title: Template Name type: string transmission_id: format: uuid title: Transmission Id type: string transmission_type: title: Transmission Type type: string uses_named_variables: title: Uses Named Variables type: boolean valid_count: title: Valid Count type: integer warnings: items: type: string title: Warnings type: array required: - transmission_id - name - status - transmission_type - template_name - template_language - uses_named_variables - recipient_count - valid_count - invalid_count - duplicate_count - column_mapping - phone_column - sample_errors - estimated_duration_seconds - scheduled_at - warnings - business_id title: TransmissionPreviewOut type: object ApiError: description: >- The response body of a handled API error. ``detail`` is either a plain string (FastAPI's default for an ``HTTPException`` raised with a string, and for the ``default`` fastapi-users messages like ``"Not authenticated"``) or the structured :class:`ApiErrorDetail` object described above. ``code`` is present only on the top-level shape ``aizap.core.exceptions.AppException`` produces for its own 5xx responses (``"INTERNAL_ERROR"`` / ``"DB_ERROR"``); it does not duplicate the ``code`` nested inside a structured ``detail``. properties: code: anyOf: - type: string - type: 'null' default: null title: Code detail: anyOf: - type: string - $ref: '#/components/schemas/ApiErrorDetail' title: Detail required: - detail title: ApiError type: object HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' title: Detail type: array title: HTTPValidationError type: object PreviewRowErrorOut: properties: error: title: Error type: string phone: anyOf: - type: string - type: 'null' title: Phone row_index: title: Row Index type: integer required: - row_index - phone - error title: PreviewRowErrorOut type: object ApiErrorDetail: additionalProperties: true description: |- The structured ``detail`` object some error responses carry. Several handlers (the REST API plan gate, the free-tier limits, the webhooks entitlement gate, the closed customer-service window) raise ``HTTPException(detail={"code": ..., "message": ..., ...})`` — a fixed ``code``/``message`` pair plus extra fields specific to that error. ``extra="allow"`` keeps those fields in the documented shape instead of dropping them. properties: code: title: Code type: string message: title: Message type: string required: - code - message title: ApiErrorDetail type: object ValidationError: properties: ctx: title: Context type: object input: title: Input loc: items: anyOf: - type: string - type: integer title: Location type: array msg: title: Message type: string type: title: Error Type type: string required: - loc - msg - type title: ValidationError type: object securitySchemes: bearerAuth: description: >- Personal access token (izap_pat_…) sent as Authorization: Bearer ; dashboard session JWTs are also accepted. scheme: bearer type: http ````