coss.comdocs

Upload a document

POST
/v1/sign/documents

Uploads a PDF (base64, at most 25 MB and 500 pages, not password-protected) for signature requests to use. The response lists each page's size and the text anchors found in it ({{signature:signer_1}}), which fields can be placed by. Requests can also take PDFs inline.

Authorization

bearerAuth
headerAuthorizationBearer <token>

A secret API key from the dashboard: coss_live_… for production environments, coss_test_… for sandbox environments.

Header Parameters

Coss-Version?"2026-10-10"

The API version (a date) to use for this request. Defaults to your organization's version, pinned to the latest one when it first used the API and upgraded from the dashboard. The SDK always sends the version it was built for.

Value in"2026-10-10"

Request Body

application/json
  1. body
filename*string

The file's name, ending in .pdf.

Length1 <= length <= 255
content*string

The PDF's bytes, base64-encoded (at most 25 MB decoded).

Length1 <= length

Response Body

The uploaded document.

application/json
  1. response
object*"sign_document"
Value in"sign_document"
id*string
filename*string
size*integer

Bytes.

sha256*string

Hex SHA-256 of the uploaded bytes.

page_count*integer
pages*array<>

Each page's size, in order.

anchors*array<>

Text anchors ({{signature:signer_1}}) found in the document, which fields can be placed by.

sandbox*boolean
created_at*string
Formatdate-time
import { Coss } from "coss";const coss = new Coss({  apiKey: process.env.COSS_API_KEY,  baseUrl: "https://api.coss.com",});const { data, error } = await coss.sign.documents.upload({  filename: "agreement.pdf",  content: "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",});
{  "object": "sign_document",  "id": "sdoc_01k7c8m4q2f3e9v6t5r1n0p8yz",  "filename": "agreement.pdf",  "size": 48213,  "sha256": "9f2c6c0f0e1d4b7a8c5e3f2a1b0c9d8e7f6a5b4c3d2e1f0a9b8c7d6e5f4a3b2c",  "page_count": 2,  "pages": [    {      "width": 612,      "height": 792    },    {      "width": 612,      "height": 792    }  ],  "anchors": [    {      "text": "{{signature:signer_1}}",      "page": 2,      "x": 72,      "y": 640,      "width": 140,      "height": 12    }  ],  "sandbox": false,  "created_at": "2026-10-26T15:04:05.000Z"}