> ## Documentation Index > Fetch the complete documentation index at: https://docs.lobbystack.com/llms.txt > Use this file to discover all available pages before exploring further. # Start a file upload > Reserves an upload for a document up to 10 MB and returns where to send it. Send the file's bytes with PUT to upload_url, with exactly upload_headers, within about 15 minutes. Then call POST /knowledge/uploads/{upload_id}/complete. An unfinished upload expires after a day. ## OpenAPI ````yaml /api-reference/openapi.json post /knowledge/uploads openapi: 3.1.0 info: title: LobbyStack API version: v1 description: >- Read calls, contacts, appointments and messages, book appointments, and subscribe to webhooks. Authenticate with an API key in the Authorization header. A platform key also names the business it acts on in the LobbyStack-Business header. Each key allows 120 requests per minute by default. servers: - url: https://app.lobbystack.com/api/v1 security: - bearerAuth: [] tags: - name: Business - name: Receptionist - name: Billing - name: Phone numbers - name: Onboarding - name: Team - name: Website chat - name: Calendars - name: Notifications - name: Calls - name: Contacts - name: Appointments - name: Messages - name: Knowledge - name: Webhooks - name: Platform paths: /knowledge/uploads: post: tags: - Knowledge summary: Start a file upload description: >- Reserves an upload for a document up to 10 MB and returns where to send it. Send the file's bytes with PUT to upload_url, with exactly upload_headers, within about 15 minutes. Then call POST /knowledge/uploads/{upload_id}/complete. An unfinished upload expires after a day. operationId: createKnowledgeUpload parameters: - name: LobbyStack-Business in: header description: >- The business a platform key acts on. Required with a platform key. A per-business key may leave it out; if it sends one, it must be the key's own business. schema: type: string format: uuid requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/KnowledgeUploadCreate' responses: '201': description: Created content: application/json: schema: type: object required: - data properties: data: $ref: '#/components/schemas/KnowledgeUpload' '400': description: >- The request is invalid (invalid_request), or a platform key sent no LobbyStack-Business header (business_required). content: application/json: schema: $ref: '#/components/schemas/Error' '401': description: The API key is missing, invalid, or revoked (unauthorized). content: application/json: schema: $ref: '#/components/schemas/Error' '403': description: >- Refused. insufficient_scope: the key lacks the knowledge:write scope. forbidden: a per-business key named another business in LobbyStack-Business. key_owner_inactive: the person the key acts for can't any more: a per-business key's creator is no longer an owner or admin, or a platform key's owner_email has no verified LobbyStack account. content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: A platform key named a business it cannot act on (not_found). content: application/json: schema: $ref: '#/components/schemas/Error' '409': description: The request conflicts with the current state. content: application/json: schema: $ref: '#/components/schemas/Error' '429': description: >- Too many requests (rate_limited). Wait for the Retry-After header's number of seconds. content: application/json: schema: $ref: '#/components/schemas/Error' headers: Retry-After: schema: type: integer description: Seconds to wait. security: - bearerAuth: [] components: schemas: KnowledgeUploadCreate: type: object properties: file_name: type: string minLength: 1 maxLength: 255 pattern: '[^.]' description: The file's name, such as prices.pdf. content_type: type: string enum: - application/pdf - >- application/vnd.openxmlformats-officedocument.wordprocessingml.document - text/plain - text/markdown - image/jpeg - image/png - image/webp - image/tiff description: >- PDF, Word (DOCX), plain text, Markdown, or a JPEG, PNG, WebP or TIFF image. length: type: integer exclusiveMinimum: 0 maximum: 10485760 description: The file's size in bytes, up to 10 MB. checksum_sha256: type: string pattern: ^[A-Za-z0-9+/]{43}=$ description: The base64-encoded SHA-256 of the file's bytes. required: - file_name - content_type - length - checksum_sha256 additionalProperties: false KnowledgeUpload: type: object properties: upload_id: type: string format: uuid description: Stable identifier (UUID). upload_url: type: string description: Send the file's bytes here with PUT. upload_headers: type: object propertyNames: type: string additionalProperties: type: string description: Send exactly these headers with the PUT. expires_at: anyOf: - type: string format: date-time description: ISO 8601 timestamp in UTC. - type: 'null' description: When upload_url stops working, about 15 minutes after it was made. required: - upload_id - upload_url - upload_headers - expires_at additionalProperties: false description: Where to send a file before completing its upload. Error: type: object properties: error: type: object properties: code: type: string enum: - invalid_request - unauthorized - forbidden - insufficient_scope - not_found - conflict - idempotency_key_reused - idempotency_request_in_progress - booking_disabled - booking_requires_confirmation - slot_unavailable - rate_limited - rate_limit_unavailable - method_not_allowed - internal_error - business_required - key_owner_inactive - plan_limit_reached message: type: string details: type: array items: type: object properties: path: type: string message: type: string required: - path - message additionalProperties: false required: - code - message additionalProperties: false required: - error additionalProperties: false securitySchemes: bearerAuth: type: http scheme: bearer description: >- An API key from Settings > API keys (lsk_...), which acts on its own business, or a platform key from the PLATFORM_API_KEYS setting (lsp_...), which onboards and manages businesses. Scopes: business:read, business:write, calls:read, contacts:read, contacts:write, appointments:read, appointments:write, messages:read, knowledge:read, knowledge:write, webhooks:manage, billing:manage, phone_numbers:manage, team:manage, businesses:create, users:create. Only platform keys can hold businesses:create and users:create. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.