> ## Documentation Index > Fetch the complete documentation index at: https://developers.huechat.ai/llms.txt > Use this file to discover all available pages before exploring further. # Create a message > Creates a new message in a conversation. Supports JSON and multipart/form-data with file attachments. ## OpenAPI ````yaml /api-reference/openapi.json post /core/accounts/{account_id}/conversations/{conversation_id}/messages openapi: 3.0.3 info: contact: name: HueChat support email: support@huechat.ai url: https://huechat.ai/contact description: >- Account-scoped REST API for HueChat: conversations, messages, contacts, inboxes, teams, agents, AI agents and knowledge, WhatsApp templates and broadcasts, workflows, chat menus, webhooks and API keys. Every route is scoped to your own account. license: name: Proprietary url: https://huechat.ai/terms termsOfService: https://huechat.ai/terms title: HueChat API version: 2.0.0 servers: - url: https://app.huechat.ai description: Production security: - bearerAuth: [] tags: - name: AI Agents description: >- Assistants you build to answer customers on their own: persona, language, guardrails, tools and a knowledge base, published to inboxes, replying in Arabic or English until they hand off to a human. Create, publish, test, monitor quality and roll back versions. - name: API Keys description: >- Scoped hc_ keys with their own scopes, rate limit, IP allowlist and expiry; rotate, revoke and read the usage log. - name: Agents description: The human agents on your account and their availability. - name: Broadcasts description: >- Send a WhatsApp template to a list of contacts from a CSV or saved audience, with scheduling, pause and resume, and delivery reports. - name: Chat Menus description: >- Numbered or button-driven menus a customer sees at the start of a conversation. - name: Contacts description: >- The people your team talks to: phone, email, name, custom attributes, labels and notes. One contact can have conversations on several channels. - name: Conversations description: >- A conversation is one thread between a contact and your team on one channel, with status, assignee, team, labels, priority and custom attributes. List, filter, search, assign, resolve and annotate them. - name: Inboxes description: >- Connected channels: a WhatsApp Business number, an Instagram or Messenger page, an email address or a website live-chat widget. Inboxes decide where a conversation comes from and who can see it. - name: Knowledge description: >- Documents, web pages and text that ground an AI agent's answers. Upload, point at a URL or paste text; HueChat indexes it and the agent cites it. - name: Messages description: >- Everything said inside a conversation: text, attachments, WhatsApp templates and interactive replies. Sending through the API delivers on the conversation's channel and shows in the inbox like any agent reply. - name: Outbound Webhooks description: >- Signed webhooks (v2): HMAC-SHA256 signature on every delivery, test events, delivery logs and secret rotation. - name: Teams description: Groups of agents used for assignment and reporting. - name: Templates description: >- Pre-approved WhatsApp message formats required by Meta for business-initiated messages. Create, sync from Meta, AI-generate, test-send and read analytics. - name: Webhooks description: >- Account webhooks (v1): a URL plus event subscriptions, as configured in the dashboard. Unsigned; prefer Outbound Webhooks for new integrations. - name: Workflows description: >- Automation flows built from triggers and steps: route, tag, reply, wait, hand off. Create, publish, version and toggle. paths: /core/accounts/{account_id}/conversations/{conversation_id}/messages: post: tags: - Messages summary: Create a message description: >- Creates a new message in a conversation. Supports JSON and multipart/form-data with file attachments. parameters: - description: Account ID in: path name: account_id required: true schema: type: integer - description: Conversation display ID in: path name: conversation_id required: true schema: type: integer requestBody: content: application/json: schema: $ref: '#/components/schemas/accounts.messageCreateRequest' example: content: Hello from the HueChat API! message_type: outgoing multipart/form-data: schema: type: object properties: content: type: string description: Message text. A message needs text or an attachment. example: Hello from the HueChat API! message_type: type: string enum: - incoming - outgoing - activity - template default: outgoing private: type: boolean default: false description: Create an internal note when true. content_type: type: string default: text description: Message content format, such as text. content_attributes: type: string description: JSON-encoded object sent as a form field. example: '{}' additional_attributes: type: string description: JSON-encoded object sent as a form field. example: '{}' echo_id: type: string description: Client correlation identifier. source_id: type: string description: External message identifier, where supported. attachments[]: type: array description: >- Repeat this multipart field for each file. Channel-specific file and size limits apply. items: type: string format: binary description: Message payload required: true responses: '200': description: OK content: application/json: schema: type: object additionalProperties: true '400': description: Bad Request content: application/json: schema: additionalProperties: type: string type: object '401': description: Unauthorized content: application/json: schema: additionalProperties: type: string type: object '404': description: Not Found content: application/json: schema: additionalProperties: type: string type: object '500': description: Internal Server Error content: application/json: schema: additionalProperties: type: string type: object security: - bearerAuth: [] x-codeSamples: - lang: bash label: JSON message source: |- curl --request POST \ --url "https://app.huechat.ai/core/accounts/${HUECHAT_ACCOUNT_ID}/conversations/${HUECHAT_CONVERSATION_ID}/messages" \ --header "Authorization: Bearer ${HUECHAT_API_KEY}" \ --header 'Content-Type: application/json' \ --data '{"content":"Hello from the HueChat API!","message_type":"outgoing"}' - lang: bash label: File attachment source: |- curl --request POST \ --url "https://app.huechat.ai/core/accounts/${HUECHAT_ACCOUNT_ID}/conversations/${HUECHAT_CONVERSATION_ID}/messages" \ --header "Authorization: Bearer ${HUECHAT_API_KEY}" \ --form-string 'content=Here is your file.' \ --form-string 'message_type=outgoing' \ --form 'attachments[]=@./example.pdf' components: schemas: accounts.messageCreateRequest: type: object properties: content: type: string description: Message text. A message needs text or an attachment. example: Hello from the HueChat API! message_type: oneOf: - type: string enum: - incoming - outgoing - activity - template - type: integer enum: - 0 - 1 - 2 - 3 default: outgoing description: >- Defaults to outgoing. Numeric values map to incoming (0), outgoing (1), activity (2), and template (3). Channel and conversation permissions still apply. private: type: boolean default: false description: Create an internal note when true. content_type: type: string default: text description: Message content format, such as text. content_attributes: type: object additionalProperties: true description: Attributes for the selected content format. additional_attributes: type: object additionalProperties: true echo_id: type: string description: Client correlation identifier. source_id: type: string description: External message identifier, where supported. securitySchemes: bearerAuth: type: http scheme: bearer description: >- Your personal access token from Settings → Profile, or a scoped API key (`hc_…`) created at Settings → Developer → API keys. Send it as `Authorization: Bearer `. ````