> ## Documentation Index > Fetch the complete documentation index at: https://cactal.ai/docs/llms.txt > Use this file to discover all available pages before exploring further. # Begin an asset upload > Step 1 of the two-step upload: validates `kind`, `mimeType`, and `byteSize`, creates the asset as `pending`, and returns presigned upload instructions. Include a one-line `description` (and `category` for images) so the asset can be found later. PUT the raw bytes to `upload.url` with exactly `upload.headers` within 15 minutes, then finalize. `image` accepts PNG, JPEG, WebP, GIF, AVIF, SVG, BMP, and ICO up to 10 MiB; `file` accepts documents, fonts, audio, video, images, ZIP, `.riv`, and `.lottie` up to 100 MiB. Unfinalized uploads are cleaned up after about an hour. ## OpenAPI ````yaml /api-reference/openapi.json post /websiteAssets openapi: 3.1.0 info: title: Cactal API version: 1.0.0 description: >- The Cactal public API. Create, edit, publish, and operate websites programmatically. Authenticate every request with an API key sent as `Authorization: Bearer `. servers: - url: https://api.cactal.ai/v1 security: - apiKey: [] tags: - name: Documentation description: >- Search and read the Cactal product documentation for concepts, guides, agent workflows, platform behavior, and API operations. - name: Feedback description: >- Submit free-form product feedback from users and agents to the Cactal feedback inbox. - name: Websites description: >- Create and manage websites — the top-level resource that owns source code, content, assets, domains, and analytics. - name: Website editors description: >- Grant, list, and revoke website-scoped editor access, and invite collaborators to a single website by email. - name: API keys description: >- Create, scope, rotate, and revoke the API keys that authenticate programmatic and agent access. - name: Source code description: >- Read and edit the framework source files of a website draft. Mutations require an edit lease. - name: Publishing description: Validate, build, publish, and roll back website versions. - name: CMS collections description: >- Define the content model: collections of structured content owned by a website. - name: CMS fields description: Manage the typed fields that make up a collection schema. - name: CMS items description: >- Create, query, publish, and organize the content entries inside a collection. - name: Domains description: >- Manage platform subdomains and custom domains, including DNS verification and the primary domain. - name: Assets description: Upload and manage website files and images served from the Cactal CDN. - name: Media generation description: >- Generate reference-guided website images that are stored as ordinary Cactal CDN assets. - name: Project Context description: >- Upload private durable reference material that the website agent can search, read, and inspect. - name: Analytics description: >- Read first-party traffic analytics for a website and export datasets as CSV. - name: Organizations description: Manage organizations, members, and organization-wide invitations. - name: Audit log description: >- Read the immutable record of actions performed in an organization by users and API keys. - name: Billing description: >- Read billing state and manage plans, site capacity, and prepaid usage balance. Every billing operation requires the organization owner role, which API keys cannot hold — today these operations are performed from the dashboard, return 403 for API-key callers, and are hidden from MCP tool lists. paths: /websiteAssets: post: tags: - Assets summary: Begin an asset upload description: >- Step 1 of the two-step upload: validates `kind`, `mimeType`, and `byteSize`, creates the asset as `pending`, and returns presigned upload instructions. Include a one-line `description` (and `category` for images) so the asset can be found later. PUT the raw bytes to `upload.url` with exactly `upload.headers` within 15 minutes, then finalize. `image` accepts PNG, JPEG, WebP, GIF, AVIF, SVG, BMP, and ICO up to 10 MiB; `file` accepts documents, fonts, audio, video, images, ZIP, `.riv`, and `.lottie` up to 100 MiB. Unfinalized uploads are cleaned up after about an hour. operationId: websiteAssets.beginUpload requestBody: required: true content: application/json: schema: type: object properties: websiteId: type: string minLength: 1 kind: type: string enum: - image - file filename: type: string minLength: 1 maxLength: 255 mimeType: type: string maxLength: 255 byteSize: type: integer exclusiveMinimum: 0 maximum: 9007199254740991 description: type: string minLength: 1 maxLength: 500 description: 'One sentence: subject, visible text, style, intended use.' category: type: string enum: - logo - icon - photo - illustration - screenshot - graphic - background - other description: What the image is. Images only. listed: description: >- Pass `false` to keep the asset out of lists until the website uses it; it is then never described automatically. Cactal sets this for images attached to agent messages. type: boolean required: - websiteId - kind - filename - mimeType - byteSize responses: '200': description: >- The pending asset id and presigned upload instructions. Next: PUT the file bytes to `upload.url`, then call `websiteAssets.finalize` with `assetId`. content: application/json: schema: type: object properties: assetId: type: string description: >- Id of the pending asset. After uploading the bytes, pass it to websiteAssets.finalize. upload: type: object properties: url: type: string description: Presigned URL to PUT the raw file bytes to. method: type: string const: PUT description: HTTP method to use against `url`. headers: type: object propertyNames: type: string additionalProperties: type: string description: >- Headers that must be sent exactly as given on the PUT because the signature is bound to the declared `Content-Type` and `Content-Length`. expiresAt: description: >- When the presigned URL stops working (15 minutes after issue). type: string format: date-time required: - url - method - headers - expiresAt additionalProperties: false description: Presigned instructions for uploading the file bytes. required: - assetId - upload additionalProperties: false '400': description: >- Validation failed. The response `message` names the first invalid field. content: application/json: schema: $ref: '#/components/schemas/ServiceError' '401': description: Missing, invalid, expired, or revoked API key. content: application/json: schema: $ref: '#/components/schemas/ServiceError' '403': description: The authenticated principal lacks the required capability. content: application/json: schema: $ref: '#/components/schemas/ServiceError' '404': description: >- The resource does not exist or is outside the principal’s access scope. content: application/json: schema: $ref: '#/components/schemas/ServiceError' '429': description: >- Rate limit exceeded. Retry after the number of seconds in the `Retry-After` header. content: application/json: schema: $ref: '#/components/schemas/ServiceError' components: schemas: ServiceError: type: object required: - kind - message description: >- Canonical error body returned by every non-2xx response. Extra fields carry error-specific details. properties: kind: type: string enum: - validation - unauthorized - forbidden - not_found - conflict - rate_limited - internal description: Stable, machine-readable error category. message: type: string description: Human-readable explanation of the failure. suggestion: type: string description: >- What to do next when the failure has a known fix; may name the exact operation to call. validValues: type: array items: type: string description: The acceptable values for the failing field, when the set is closed. additionalProperties: true securitySchemes: apiKey: type: http scheme: bearer description: >- Cactal API key. Create one in the dashboard or via `POST /apiKeys`. The plaintext key is shown once at creation. ````