> ## Documentation Index > Fetch the complete documentation index at: https://docs.greentick.ai/llms.txt > Use this file to discover all available pages before exploring further. # Send a WhatsApp message > Send a session text message or an approved WhatsApp template. Text messages require an open customer-service window; templates can start a conversation. GreenTick templates use named variables only. The to field is cleaned to digits and validated with country code (same rules as dashboard contacts) before calling WhatsApp. Template requests may include scheduledAt. An offset or Z is stored as that instant. A value without a zone is read in the account profile timezone from GET /api-key. Text messages cannot be scheduled. ## OpenAPI ````yaml /openapi.json post /messages openapi: 3.1.0 info: title: GreenTick Developer API version: 1.0.0 summary: WhatsApp messaging, contacts, workflows, and webhooks description: >- Use GreenTick's REST API to send WhatsApp messages, synchronize contacts, trigger workflows, and receive signed event webhooks. Each API key belongs to one connected phone number. contact: name: GreenTick Support url: https://greentick.ai servers: - url: https://api.greentick.ai/v1 description: GreenTick API v1 security: [] tags: - name: System description: Health and API metadata - name: Messages description: Send WhatsApp messages - name: Conversations description: List inbox threads and fetch message history - name: Templates description: Discover approved templates and their variables - name: Contacts description: Synchronize customer contacts - name: Labels description: Contact label catalog for the connected phone number - name: Attributes description: Contact custom attribute definitions for the connected phone number - name: Phone numbers description: WhatsApp sending line for this phone number - name: Automations description: List enrollable automations and start one for a contact - name: Workflow hooks description: Trigger GreenTick automations from external systems - name: Webhooks description: Subscribe Zapier, Make.com, or your own server to GreenTick events - name: API key description: Check the Bearer API key and account timezone - name: MCP platform description: Limits, usage, and shared connector behavior - name: Media description: Host customer-supplied files - name: Workflows description: Create, publish, and export automations - name: Flows description: WhatsApp Flows - name: AI bots description: AI bots and knowledge - name: Broadcasts description: Template broadcasts - name: Catalogs description: Commerce catalogs, products, and orders - name: Ads description: Click-to-WhatsApp ads and conversions paths: /messages: post: tags: - Messages summary: Send a WhatsApp message description: >- Send a session text message or an approved WhatsApp template. Text messages require an open customer-service window; templates can start a conversation. GreenTick templates use named variables only. The to field is cleaned to digits and validated with country code (same rules as dashboard contacts) before calling WhatsApp. Template requests may include scheduledAt. An offset or Z is stored as that instant. A value without a zone is read in the account profile timezone from GET /api-key. Text messages cannot be scheduled. operationId: sendMessage requestBody: required: true content: application/json: schema: oneOf: - $ref: '#/components/schemas/TextMessageRequest' - $ref: '#/components/schemas/TemplateMessageRequest' discriminator: propertyName: type examples: text: summary: 'Example: Text message' value: to: '919876543210' type: text phoneNumberRef: 668f1a2b3c4d5e6f7a8b9c0a text: Hello from GreenTick templateSimple: summary: 'Example: Template with named variables' value: to: '919876543210' type: template phoneNumberRef: 668f1a2b3c4d5e6f7a8b9c0a template: name: order_update language: en_US variables: customer_name: Akshay order_id: ord_123 templateMediaHeader: summary: 'Example: Template with image header' value: to: '919876543210' type: template phoneNumberRef: 668f1a2b3c4d5e6f7a8b9c0a template: name: promo_banner language: en_US variables: offer: 20% OFF headerMediaUrl: https://example.com/banner.jpg templateDynamicUrl: summary: 'Example: Template with dynamic URL button' value: to: '919876543210' type: template phoneNumberRef: 668f1a2b3c4d5e6f7a8b9c0a template: name: order_update language: en_US variables: customer_name: Akshay order_id: ord_123 dynamicURLVariable: ord_123 templateCopyCode: summary: 'Example: Template with copy code button' value: to: '919876543210' type: template phoneNumberRef: 668f1a2b3c4d5e6f7a8b9c0a template: name: winter_sale_coupon language: en_US variables: customer_name: Akshay discount: 30% copyCodeVariable: WINTER25 responses: '201': description: Message accepted by WhatsApp content: application/json: schema: $ref: '#/components/schemas/MessageResponse' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' security: - apiKey: [] components: schemas: TextMessageRequest: type: object required: - to - type - text - phoneNumberRef properties: to: type: string example: '919876543210' description: >- Recipient phone with country code. Non-digits are stripped and leading zeros removed, then validated (e.g. +91 98765 43210 → 919876543210). Invalid numbers return 400 INVALID_TO. type: type: string const: text text: type: string maxLength: 4096 phoneNumberRef: type: string description: GreenTick phone line ref from GET /phone-numbers (ref field). example: 668f1a2b3c4d5e6f7a8b9c0a TemplateMessageRequest: type: object required: - to - type - phoneNumberRef - template properties: to: type: string example: '919876543210' description: >- Recipient phone with country code. Non-digits are stripped and leading zeros removed, then validated (e.g. +91 98765 43210 → 919876543210). Invalid numbers return 400 INVALID_TO. type: type: string const: template phoneNumberRef: type: string description: GreenTick phone line ref from GET /phone-numbers (ref field). example: 668f1a2b3c4d5e6f7a8b9c0a template: type: object required: - name - language properties: name: type: string example: order_update language: description: >- Template language code. Name + language uniquely identifies the template. oneOf: - type: string example: en_US - type: object required: - code properties: code: type: string example: en_US variables: type: object additionalProperties: type: string description: >- Named variable map for header and body placeholders. Keys must match variables[].name from GET /templates (e.g. customer_name, order_id). Button-specific values use template.dynamicURLVariable and template.copyCodeVariable. example: customer_name: Akshay order_id: ord_123 dynamicURLVariable: type: string description: >- Suffix value for dynamic URL buttons ({{1}}). Required when GET /templates returns requiresDynamicURLVariable: true. example: ord_123 copyCodeVariable: type: string maxLength: 20 description: >- Coupon or code copied to the clipboard. Required when GET /templates returns requiresCopyCodeVariable: true. Max 20 characters. example: WINTER25 headerMediaUrl: type: string description: >- Optional public URL for header media when the template has an IMAGE, VIDEO, or DOCUMENT header. When omitted, GreenTick sends the template's approved sample media (header.example). Required only when GET /templates returns header.requiresMediaUrl: true. GreenTick verifies type and size before send: JPEG/PNG max 5 MB, MP4 max 16 MB, PDF max 100 MB. example: https://example.com/banner.jpg scheduledAt: type: string description: >- Optional ISO datetime for a template only. Include an offset or Z to store that instant, for example 2026-10-25T09:00:00-04:00. Without a zone, the time is read in the account profile timezone. Must be at least 5 minutes from now and within 30 days. A success returns scheduled, scheduledAt, and scheduledId and does not mean the message was delivered. example: '2026-10-25T09:00:00+05:30' MessageResponse: type: object properties: success: type: boolean example: true data: type: object properties: messageId: type: string wamid: type: string description: WhatsApp message ID conversationId: type: string message: $ref: '#/components/schemas/ConversationMessage' ConversationMessage: type: object description: >- Normalized message row. Returned on POST /messages (data.message) and in GET /conversations/{id}/messages. properties: id: type: string wamid: type: string direction: type: string enum: - inbound - outbound type: type: string description: text | template | image | video | document | audio | sticker | … text: type: string description: Human-readable preview text. createdAt: type: string format: date-time deliveryStatus: type: string nullable: true enum: - pending - sent - delivered - read - failed - deleted - null description: Latest outbound delivery state. deliveryHistory: type: array items: $ref: '#/components/schemas/MessageDeliveryHistoryEntry' repliedBy: type: string template: allOf: - $ref: '#/components/schemas/MessageTemplatePayload' nullable: true mediaId: type: string isRevoked: type: boolean MessageDeliveryHistoryEntry: type: object description: >- One delivery state change on an outbound message, ordered oldest to newest. required: - status - timestamp properties: status: type: string enum: - pending - sent - delivered - read - failed - deleted timestamp: type: string format: date-time errorCode: type: integer nullable: true description: Meta error code when status is failed. errorTitle: type: string description: Short error title when status is failed. errorMessage: type: string description: Human-readable error detail when status is failed. MessageTemplatePayload: type: object description: >- Sent template snapshot on template messages. Not the same as the GET /templates catalog object. properties: name: type: string example: order_update language: type: string example: en_US templateCategory: type: string enum: - MARKETING - UTILITY - AUTHENTICATION parameterFormat: type: string const: NAMED components: type: array description: >- Approved Meta template structure (HEADER, BODY, FOOTER, BUTTONS) with placeholders. items: type: object additionalProperties: true variableValues: type: object additionalProperties: type: string description: Resolved named variables used when the message was sent. example: customer_name: Akshay order_id: ord_123 headerComponent: type: object nullable: true description: >- Send-time header component for media headers (image/video/document link or id). additionalProperties: true responses: BadRequest: description: Invalid request content: application/json: schema: type: object required: - success - code - message properties: success: type: boolean example: false code: type: string example: INVALID_TO message: type: string example: to (E.164 phone) is required Unauthorized: description: Missing, invalid, or revoked API key content: application/json: schema: type: object required: - success - code - message properties: success: type: boolean example: false code: type: string example: INVALID_TO message: type: string example: to (E.164 phone) is required Forbidden: description: >- Plan expired (PLAN_EXPIRED) or phone number is not this API key’s connected phone number content: application/json: schema: type: object required: - success - code - message properties: success: type: boolean example: false code: type: string example: INVALID_TO message: type: string example: to (E.164 phone) is required securitySchemes: apiKey: type: http scheme: bearer bearerFormat: gt_live_… description: >- Create an API key in GreenTick Developer settings. Send it as Authorization: Bearer gt_live_… (Bearer prefix required). ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.