> ## 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. # Upload a signed respondent attachment > Signed session headers bind file to tenant, form, immutable version and question. 20 MiB/file ; 10 files or 50 MiB/session ; 1,000 or 1 GiB/form/UTC day; positive question.max adds MiB limit. Accepted inspected images/PDF/text/CSV/audio/video; no SVG/HTML/scripts/archives. video_audio accepts media only. Store returned receipt unchanged. ## OpenAPI ````yaml /api-reference/openapi.json post /api/v2/forms/{publicCode}/assets 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, Customer CDP, Sales CRM, forms, appointments, inboxes, teams, agents, AI agents and knowledge, WhatsApp templates and broadcasts, workflows and chat menus. Authenticate with account-scoped 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: Agents description: The human agents on your account and their availability. - 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: 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: Forms description: >- Form management, assets, delivery, respondent sessions, submissions, scheduling, reports and AI-assisted authoring in one group. - 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: Sales CRM description: >- The full tenant-scoped Sales workspace: Leads, Companies, Deals, tasks, products, price books, quotes, payments, forecasts, reports and settings. - 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: Workflows description: >- Automation flows built from triggers and steps: route, tag, reply, wait, hand off. Create, publish, version and toggle. paths: /api/v2/forms/{publicCode}/assets: parameters: - $ref: '#/components/parameters/publicCode' post: tags: - Forms summary: Upload a signed respondent attachment description: >- Signed session headers bind file to tenant, form, immutable version and question. 20 MiB/file ; 10 files or 50 MiB/session ; 1,000 or 1 GiB/form/UTC day; positive question.max adds MiB limit. Accepted inspected images/PDF/text/CSV/audio/video; no SVG/HTML/scripts/archives. video_audio accepts media only. Store returned receipt unchanged. operationId: postApiV2FormsPubliccodeAssets parameters: - $ref: '#/components/parameters/formSession' - $ref: '#/components/parameters/formInvite' requestBody: required: true content: multipart/form-data: schema: type: object properties: file: type: string format: binary question_id: type: string required: - file - question_id responses: '201': description: Success content: application/json: schema: type: object properties: asset: $ref: '#/components/schemas/AssetReceipt' '400': $ref: '#/components/responses/BadRequest' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '409': $ref: '#/components/responses/Conflict' '410': $ref: '#/components/responses/Gone' '413': $ref: '#/components/responses/TooLarge' '422': $ref: '#/components/responses/ValidationError' '429': $ref: '#/components/responses/RateLimited' '503': $ref: '#/components/responses/Unavailable' security: [] components: parameters: publicCode: name: publicCode in: path required: true schema: type: string minLength: 8 maxLength: 24 formSession: name: X-Form-Session in: header required: true schema: type: string description: Signed session from GET /forms/{publicCode}. formInvite: name: X-Form-Invitation in: header schema: type: string description: Invitation bearer token when using a recipient link. schemas: AssetReceipt: type: object properties: asset_id: type: string format: uuid filename: type: string minLength: 1 maxLength: 180 mime_type: type: string byte_size: type: integer minimum: 1 maximum: 20971520 required: - asset_id - filename - mime_type - byte_size Error: type: object properties: error: type: string responses: BadRequest: description: Malformed request, invalid ID/filter or unknown top-level field. content: application/json: schema: $ref: '#/components/schemas/Error' Forbidden: description: Invitation, session, membership, or consent requirement not met. content: application/json: schema: $ref: '#/components/schemas/Error' NotFound: description: Form not found in the account or not publicly available. content: application/json: schema: $ref: '#/components/schemas/Error' Conflict: description: Stale version, duplicate response, or already used invitation. content: application/json: schema: $ref: '#/components/schemas/Error' Gone: description: Published expiry or response cap reached. content: application/json: schema: $ref: '#/components/schemas/Error' TooLarge: description: Request body, upload or CSV row limit exceeded. content: application/json: schema: $ref: '#/components/schemas/Error' ValidationError: description: The request or definition is invalid. content: application/json: schema: $ref: '#/components/schemas/Error' RateLimited: description: >- Public admission, upload or AI quota exceeded. Reserved AI failures count. content: application/json: schema: $ref: '#/components/schemas/Error' Unavailable: description: Dependency/configuration unavailable; fail closed. content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: bearerAuth: type: http scheme: bearer description: >- Your personal access token where supported, or a scoped API key (`hc_…`) created inside HueChat at Account → Developer API. Send it as `Authorization: Bearer `. ````