---
title: "Upload chunk · Documents · COUNT Partner API"
description: "Uploads a single chunk of a multipart upload. POST /partners/documents/chunk-upload/chunk"
canonical: "https://developers.getcount.com/reference/documents/chunk-upload-chunk"
source: "https://developers.getcount.com/reference/documents/chunk-upload-chunk"
---
[Documents](https://developers.getcount.com/reference/documents) / Upload chunk

# Upload chunk

POST `/partners/documents/chunk-upload/chunk`

Uploads a single chunk of a multipart upload.

Send multipart/form-data with `file`, `blockId`, and `uploadProgressId`. Sign with empty-object body hash.

HMAC signature + Bearer access token

[Try this request](https://developers.getcount.com/tools/try-it?method=POST&path=%2Fpartners%2Fdocuments%2Fchunk-upload%2Fchunk)

[Customers API](https://developers.getcount.com/reference/customers) [Projects API](https://developers.getcount.com/reference/projects)

#### Request body

`file` string required

Binary chunk sent as multipart form field.

`blockId` string required

Identifier for this chunk block.

`uploadProgressId` string required

Upload session identifier from initiate.

#### Responses

`200` Chunk accepted.

`401` Missing or invalid HMAC signature, expired timestamp, or invalid Bearer token. [Troubleshoot](https://developers.getcount.com/getting-started/errors#error-401)

`403` The credential does not have access to this workspace or resource. [Troubleshoot](https://developers.getcount.com/getting-started/errors#error-403)

`429` Rate limit exceeded (100 requests per minute per clientId). Retry after the Retry-After header. [Troubleshoot](https://developers.getcount.com/getting-started/errors#error-429)

[Previous POST Initiate chunked upload](https://developers.getcount.com/reference/documents/chunk-upload-initiate) [Next POST Complete chunked upload](https://developers.getcount.com/reference/documents/chunk-upload-complete)

POST `https://api.getcount.com/partners/documents/chunk-upload/chunk`

Request

```javascript
import crypto from 'node:crypto';

const BASE_URL = 'https://api.getcount.com';
const CLIENT_ID = process.env.COUNT_CLIENT_ID;
const CLIENT_SECRET = process.env.COUNT_CLIENT_SECRET;
const ACCESS_TOKEN = process.env.COUNT_ACCESS_TOKEN;

const method = 'POST';
const signingPath = '/documents/chunk-upload/chunk';
const timestamp = Math.floor(Date.now() / 1000).toString();
const bodyString = '';

const bodyHash = '';
const baseString = `${method}:${signingPath}:${timestamp}:${bodyHash}`;
const signature = crypto.createHmac('sha256', CLIENT_SECRET).update(baseString).digest('hex');

const response = await fetch(`${BASE_URL}/partners/documents/chunk-upload/chunk`, {
  method,
  headers: {
    'x-client-id': CLIENT_ID,
    'x-timestamp': timestamp,
    'x-signature': signature,
    Authorization: `Bearer ${ACCESS_TOKEN}`,
  },
});

console.log(await response.json());
```

Response · 200

```json
{
  "status": "success",
  "data": {
    "blockId": "block-1",
    "uploaded": true
  }
}
```