> ## 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. # Send a template message to a chat > Sends an approved WhatsApp template into the conversation. This is the only way to reach a customer outside the 24-hour customer-service window. A rendered copy is stored so agents see what was sent. ## OpenAPI ````yaml /api-reference/openapi.json post /api/v1/chats/{chat_id}/messages/template 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/chats/{chat_id}/messages/template: post: tags: - messages summary: Send a template message to a chat description: >- Sends an approved WhatsApp template into the conversation. This is the only way to reach a customer outside the 24-hour customer-service window. A rendered copy is stored so agents see what was sent. operationId: sendChatTemplateMessage parameters: - in: path name: chat_id required: true schema: format: uuid title: Chat Id type: string requestBody: content: application/json: schema: $ref: '#/components/schemas/ChatTemplateSendRequest' required: true responses: '200': content: application/json: schema: $ref: '#/components/schemas/SendChatTemplateMessageOut' 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: ChatTemplateSendRequest: description: Send an approved template into an existing live-chat conversation. properties: template_id: format: uuid title: Template Id type: string variables: additionalProperties: type: string description: Body/button variable values, keyed '1','2',… title: Variables type: object required: - template_id title: ChatTemplateSendRequest type: object SendChatTemplateMessageOut: description: Response for ``POST /chats/{chat_id}/messages/template``. properties: user_message: $ref: '#/components/schemas/ChatMessageSummaryOut' required: - user_message title: SendChatTemplateMessageOut 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 ChatMessageSummaryOut: description: A chat message as embedded in the send-message responses below. properties: content: anyOf: - type: string - type: 'null' title: Content error_code: anyOf: - type: integer - type: 'null' title: Error Code error_reason: anyOf: - type: string - type: 'null' title: Error Reason id: format: uuid title: Id type: string message_sid: anyOf: - type: string - type: 'null' title: Message Sid no_reply: title: No Reply type: boolean receiver: anyOf: - type: string - type: 'null' title: Receiver sender_user_id: anyOf: - format: uuid type: string - type: 'null' title: Sender User Id status: anyOf: - $ref: '#/components/schemas/ChatMessageStatus' - type: 'null' timestamp: format: date-time title: Timestamp type: string updated_at: anyOf: - format: date-time type: string - type: 'null' title: Updated At required: - id - content - no_reply - timestamp - status - error_code - error_reason - sender_user_id title: ChatMessageSummaryOut 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 ChatMessageStatus: enum: - new - queued - sending - sent - failed - delivered - undelivered - receiving - received - accepted - scheduled - read - played - cancelled title: ChatMessageStatus type: string securitySchemes: bearerAuth: description: >- Personal access token (izap_pat_…) sent as Authorization: Bearer ; dashboard session JWTs are also accepted. scheme: bearer type: http ````