> ## Documentation Index > Fetch the complete documentation index at: https://docs.zavu.dev/llms.txt > Use this file to discover all available pages before exploring further. # Send reaction to message > Send an emoji reaction to an existing WhatsApp message. Reactions are only supported for WhatsApp messages. ## OpenAPI ````yaml /openapi.json post /v1/messages/{messageId}/reactions openapi: 3.0.3 info: title: Zavu Unified Messaging Layer API version: 0.2.0 description: > Unified multi-channel messaging API for Zavu. Supported channels: - **SMS**: Simple text messages - **WhatsApp**: Rich messaging with media, buttons, lists, CTA URL buttons, and templates - **Telegram**: Bot messaging with text, media, and interactive elements - **Email**: Transactional emails via Amazon SES Design goals: - Simple `send()` entrypoint for developers - Project-level authentication via Bearer token - Support for all WhatsApp message types (text, image, video, audio, document, sticker, location, contact, buttons, list, cta_url, reaction, template) - If a non-text message type is sent, WhatsApp channel is used automatically - 24-hour WhatsApp conversation window enforcement - Universal `to` field accepts phone numbers (E.164), email addresses, or numeric chat IDs (Telegram/Instagram) servers: - url: https://api.zavu.dev security: - bearerAuth: [] paths: /v1/messages/{messageId}/reactions: post: summary: Send reaction to message description: >- Send an emoji reaction to an existing WhatsApp message. Reactions are only supported for WhatsApp messages. operationId: sendReaction parameters: - $ref: '#/components/parameters/MessageIdParam' - $ref: '#/components/parameters/SenderHeader' requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/ReactionRequest' example: emoji: 👍 responses: '202': description: Reaction accepted for delivery. content: application/json: schema: $ref: '#/components/schemas/MessageResponse' '400': description: Invalid request or message is not from WhatsApp. content: application/json: schema: $ref: '#/components/schemas/Error' examples: not_whatsapp: summary: Not a WhatsApp message value: code: bad_request message: Reactions are only supported for WhatsApp messages '401': description: Unauthorized. content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: Message not found. content: application/json: schema: $ref: '#/components/schemas/Error' security: - bearerAuth: [] components: parameters: MessageIdParam: name: messageId in: path required: true schema: type: string SenderHeader: name: Zavu-Sender in: header required: false description: >- Optional sender profile ID. If omitted, the project's default sender will be used. schema: type: string example: sender_12345 schemas: ReactionRequest: type: object required: - emoji properties: emoji: type: string description: Single emoji character to react with. example: 👍 MessageResponse: type: object required: - message properties: message: $ref: '#/components/schemas/Message' Error: type: object required: - code - message properties: code: type: string example: invalid_request message: type: string example: Phone number is invalid details: type: object additionalProperties: true Message: type: object required: - id - to - status - channel - messageType - createdAt properties: id: type: string example: jd7x2k3m4n5p6q7r8s9t0 to: type: string example: '+56912345678' from: type: string example: '+13125551212' senderId: type: string example: sender_12345 channel: $ref: '#/components/schemas/Channel' messageType: $ref: '#/components/schemas/MessageType' status: $ref: '#/components/schemas/MessageStatus' text: type: string description: Text content or caption. content: $ref: '#/components/schemas/MessageContent' providerMessageId: type: string description: Message ID from the delivery provider. errorCode: type: string nullable: true errorMessage: type: string nullable: true cost: type: number nullable: true description: MAU cost in USD (charged for first contact of the month). costProvider: type: number nullable: true description: Provider cost in USD (Telnyx, SES, etc.). costTotal: type: number nullable: true description: Total cost in USD (MAU + provider cost). metadata: type: object additionalProperties: type: string createdAt: type: string format: date-time updatedAt: type: string format: date-time Channel: type: string description: Delivery channel. Use 'auto' for intelligent routing. enum: - auto - sms - sms_oneway - whatsapp - telegram - email - instagram - voice MessageType: type: string description: >- Type of message. Non-text types are supported by WhatsApp and Telegram (varies by type). enum: - text - image - video - audio - document - sticker - location - contact - buttons - list - cta_url - reaction - template MessageStatus: type: string enum: - queued - sending - sent - delivered - read - failed - received - pending_url_verification MessageContent: type: object description: Content for non-text message types (WhatsApp and Telegram). properties: mediaUrl: type: string description: URL of the media file (for image, video, audio, document, sticker). example: https://example.com/image.jpg mediaId: type: string description: WhatsApp media ID if already uploaded. mimeType: type: string description: MIME type of the media. example: image/jpeg filename: type: string description: Filename for documents. example: invoice.pdf latitude: type: number description: Latitude for location messages. longitude: type: number description: Longitude for location messages. locationName: type: string description: Name of the location. locationAddress: type: string description: Address of the location. contacts: type: array description: Contact cards for contact messages. items: type: object properties: name: type: string phones: type: array items: type: string buttons: type: array description: Interactive buttons (max 3). maxItems: 3 items: type: object required: - id - title properties: id: type: string maxLength: 256 title: type: string maxLength: 20 listButton: type: string description: Button text for list messages. maxLength: 20 sections: type: array description: Sections for list messages. items: type: object required: - title - rows properties: title: type: string rows: type: array maxItems: 10 items: type: object required: - id - title properties: id: type: string title: type: string maxLength: 24 description: type: string maxLength: 72 ctaDisplayText: type: string description: Button label for cta_url messages. maxLength: 20 example: See Dates ctaUrl: type: string format: uri description: >- Destination URL opened in the device's default browser when the button is tapped. Used with messageType=cta_url. WhatsApp requires HTTPS in production. example: https://example.com/schedule ctaHeaderType: type: string description: Optional header type for cta_url messages. enum: - text - image - video - document ctaHeaderText: type: string description: Header text when ctaHeaderType is 'text'. maxLength: 60 ctaHeaderMediaUrl: type: string format: uri description: >- Public HTTPS URL of the header media when ctaHeaderType is 'image', 'video', or 'document'. WhatsApp fetches this URL — it must be publicly reachable and return the declared content type. footerText: type: string description: Optional footer text for cta_url messages. maxLength: 60 example: Dates subject to change. emoji: type: string description: Emoji for reaction messages. reactToMessageId: type: string description: Message ID to react to. templateId: type: string description: Template ID for template messages. templateVariables: type: object description: >- Variables for body placeholders. Keys are positions (1, 2, 3, ...) matching the order placeholders appear in the template body. additionalProperties: type: string example: '1': John '2': ORD-12345 templateButtonVariables: type: object description: >- Variables for dynamic button placeholders (URL buttons and OTP buttons). Keys are the button index (0, 1, 2) in the template's `buttons` array — not the placeholder name. Values substitute the `{{1}}` placeholder inside that button's URL. **WhatsApp constraints:** - URL buttons only accept `{{1}}` — positional, numeric, no whitespace, no name. Named placeholders like `{{token}}` are stored as literal URL text by Meta and cannot be substituted. - At most one placeholder per URL button. - A template may have at most three buttons. - Static URL buttons (no placeholder) and `quick_reply` buttons are not included here. additionalProperties: type: string example: '0': abc-report-token securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT ````