Attachments API

Attach supporting files — such as a purchase order or a signed contract — to an invoice. An attachment links an uploaded file to a document. Upload the file first via the Files API, then reference the returned file ID here.

List Attachments

GET /api/v1/documents/{document_id}/attachments

Returns all attachments for a document, newest first.

Response:

{
  "data": [
    {
      "id": "att_01XYZ",
      "invoice_id": "inv_01ABC",
      "file_id": "fil_01ABC",
      "label": "Purchase Order",
      "created_at": "2026-07-20T10:00:00Z"
    }
  ]
}

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Create Attachment

POST /api/v1/documents/{document_id}/attachments

Links a previously uploaded file to the document. Upload the file with POST /api/v1/files first (see the Files API), then pass its ID as file_id. A file ID that does not exist returns a 404 not_found error.

Request:

{
  "file_id": "fil_01ABC",
  "label": "Purchase Order"
}

Field	Required	Description
file_id	Yes	ID of an uploaded file to attach
label	No	Human-readable label for the attachment

Response 200 OK:

{
  "data": {
    "id": "att_01XYZ",
    "invoice_id": "inv_01ABC",
    "file_id": "fil_01ABC",
    "label": "Purchase Order",
    "created_at": "2026-07-20T10:00:00Z"
  }
}

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Delete Attachment

DELETE /api/v1/documents/{document_id}/attachments/{attachment_id}

Removes the link between the file and the document. The underlying file itself is not deleted.

Response:

{
  "data": {
    "deleted": true
  }
}

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