> ## Documentation Index > Fetch the complete documentation index at: https://docs.fuseai.com/llms.txt > Use this file to discover all available pages before exploring further. # Attach a document to one of the hub's notes > Attaches a document to one of the hub's notes; note ids come from `notes[].id` in the hub detail. Send the file as padded base64 in `fileBase64`, up to 10,485,760 characters (about 7.5 MB of file data); allowed types are PDF, plain text, CSV, Word (.doc and .docx) and RTF. The file is stored for download only — it is not parsed into the hub's knowledge, so put the text you want the hub to learn in the note's own `text`. A note holds one attachment: a second upload answers 409 `ATTACHMENT_ALREADY_EXISTS`, and there is no replace endpoint. The response does not include a download URL; fetch one with `GET /business/knowledge-hubs/{hubId}/attachments/{noteId}`. Only the hub's owner can upload, and not while the hub is `processing`. Errors: - `404` `KNOWLEDGE_HUB_NOT_FOUND` — No hub with that id, it was deleted, or it belongs to another team. - `404` `NOTE_NOT_FOUND` — No note with that id on this hub. - `409` `ATTACHMENT_ALREADY_EXISTS` — The note already holds a document; delete the note's attachment first. - `409` `KNOWLEDGE_HUB_NOT_READY` — The hub is processing a build, update or refresh. - `403` `KNOWLEDGE_HUB_OWNER_ONLY` — You can read this teammate's hub but only its owner can upload attachments. - `422` `VALIDATION_FAILED` — Malformed base64, a file over the size cap, an unsupported contentType, or a missing field. - `500` `UNEXPECTED_ERROR` — The file could not be stored; retry. - `429` `RATE_LIMITED` — More than 30 knowledge-hub/campaign requests in a minute (or 1000 in a day). Knowledge hubs share the campaigns bucket. Requires one of the following token scopes: campaigns. ## OpenAPI ````yaml /openapi.json post /business/knowledge-hubs/{hubId}/attachments openapi: 3.1.0 info: title: Fuse Business API version: 1.0.0 description: >- External API for lists, campaigns, prospect search and contacts. Authenticate with your API token as HTTP Basic. All paths are under /api/v1. servers: - url: https://api.tryfuse.ai/api/v1 description: Production security: - basicAuth: [] tags: - name: Lists - name: Custom columns - name: Smart columns - name: Exports - name: Campaigns - name: Knowledge hubs - name: Analytics - name: Website intent - name: Account - name: Prospect search - name: Campaign steps - name: Scheduled sends - name: Campaign templates - name: Agents - name: Research - name: Company search - name: Saved searches - name: Folders - name: Contacts paths: /business/knowledge-hubs/{hubId}/attachments: post: tags: - Knowledge hubs summary: Attach a document to one of the hub's notes description: >- Attaches a document to one of the hub's notes; note ids come from `notes[].id` in the hub detail. Send the file as padded base64 in `fileBase64`, up to 10,485,760 characters (about 7.5 MB of file data); allowed types are PDF, plain text, CSV, Word (.doc and .docx) and RTF. The file is stored for download only — it is not parsed into the hub's knowledge, so put the text you want the hub to learn in the note's own `text`. A note holds one attachment: a second upload answers 409 `ATTACHMENT_ALREADY_EXISTS`, and there is no replace endpoint. The response does not include a download URL; fetch one with `GET /business/knowledge-hubs/{hubId}/attachments/{noteId}`. Only the hub's owner can upload, and not while the hub is `processing`. Errors: - `404` `KNOWLEDGE_HUB_NOT_FOUND` — No hub with that id, it was deleted, or it belongs to another team. - `404` `NOTE_NOT_FOUND` — No note with that id on this hub. - `409` `ATTACHMENT_ALREADY_EXISTS` — The note already holds a document; delete the note's attachment first. - `409` `KNOWLEDGE_HUB_NOT_READY` — The hub is processing a build, update or refresh. - `403` `KNOWLEDGE_HUB_OWNER_ONLY` — You can read this teammate's hub but only its owner can upload attachments. - `422` `VALIDATION_FAILED` — Malformed base64, a file over the size cap, an unsupported contentType, or a missing field. - `500` `UNEXPECTED_ERROR` — The file could not be stored; retry. - `429` `RATE_LIMITED` — More than 30 knowledge-hub/campaign requests in a minute (or 1000 in a day). Knowledge hubs share the campaigns bucket. Requires one of the following token scopes: campaigns. operationId: uploadKnowledgeHubAttachment parameters: - name: hubId in: path required: true description: >- 24-character hex id of the knowledge hub (from GET /business/knowledge-hubs). schema: type: string description: >- 24-character hex id of the knowledge hub (from GET /business/knowledge-hubs). requestBody: required: true content: application/json: schema: type: object properties: noteId: type: string description: >- 24-character hex id of the note to attach the document to; a note holds at most one attachment. fileBase64: type: string maxLength: 10485760 description: >- Accepted values: standard base64 with padding — alphabet A-Z a-z 0-9 + / and a length that is a multiple of 4. A URL-safe (-_) string, an unpadded one, or one that still carries a data:...;base64, prefix answers 422 VALIDATION_FAILED. The whole JSON request body is capped at 10 MB, which puts the real ceiling at roughly 7.5 MB of file data (base64 is a third larger than the file it encodes). The bytes are stored and handed back by the download endpoint unchanged: nothing reads, extracts or indexes them, so an attachment on its own adds no knowledge to the hub — only the note's text does. filename: type: string minLength: 1 maxLength: 255 description: >- File name stored with the attachment and returned by the download endpoint (1-255 characters). Free text: it is stored verbatim, never parsed, and never checked against contentType or against the note's own filename label — an extension that contradicts contentType is accepted and changes nothing. Give it the real extension anyway, since it is the name whoever opens the download sees. contentType: type: string enum: - application/pdf - text/plain - text/csv - application/msword - >- application/vnd.openxmlformats-officedocument.wordprocessingml.document - application/rtf description: >- MIME type of the file: PDF, plain text, CSV, Word (.doc or .docx) or RTF. required: - noteId - fileBase64 - filename - contentType responses: '201': description: Success headers: RateLimit-Limit: schema: type: integer description: Requests permitted in the current window. RateLimit-Remaining: schema: type: integer description: Requests remaining in the current window. RateLimit-Reset: schema: type: integer description: Seconds until the current window resets. content: application/json: schema: type: object required: - attachment properties: attachment: type: object required: - noteId - filename - contentType - byteSize properties: noteId: type: string description: The note the document is attached to. filename: type: - string - 'null' description: The file name as stored. contentType: type: - string - 'null' enum: - application/pdf - text/plain - text/csv - application/msword - >- application/vnd.openxmlformats-officedocument.wordprocessingml.document - application/rtf - null byteSize: type: - integer - 'null' description: Size of the stored file in bytes. example: attachment: noteId: 68a1f8509c41d20014b3ee55 filename: positioning.pdf contentType: application/pdf byteSize: 284913 '400': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '401': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '402': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '403': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '404': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '409': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '422': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '429': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' '500': description: Error content: application/json: schema: $ref: '#/components/schemas/Error' security: - basicAuth: [] components: schemas: Error: type: object properties: error: type: object properties: code: type: string message: type: string param: type: - string - 'null' doc_url: type: - string - 'null' request_id: type: - string - 'null' required: - code - message required: - error securitySchemes: basicAuth: type: http scheme: basic description: >- Your API token (`af_…`) as the Basic-auth username, with an empty password. ````