> ## Documentation Index
> Fetch the complete documentation index at: https://docs.squarecloud.app/llms.txt
> Use this file to discover all available pages before exploring further.

# Blob Chunked Upload Init

> This documentation provides a comprehensive overview of the POST /v1/objects/chunked endpoint of the SquareCloud Blob API.

<ParamField header="Authorization" type="string" placeholder="API Key" required>
  The API key for your account. You can find this in your [account settings](https://squarecloud.app/en/account/security).
</ParamField>

Chunked Init opens a chunked upload, the flow for files above the 100 MB single-request cap, up to **1 GiB**. It reserves the object's key and returns an opaque `upload` token that you carry through the three follow-up calls: [Chunked Part](/en/blob-reference/endpoint/chunked-part) to send each chunk, [Chunked Complete](/en/blob-reference/endpoint/chunked-complete) to seal the object, and [Chunked Abort](/en/blob-reference/endpoint/chunked-abort) to cancel.

There is **no server-side session**: the token is the whole upload state, so persist it if the upload spans a page reload. A client that loses its token cannot cancel the upload, and the stored chunks count against the account's limit of **8 open uploads** until the service reclaims them (about 24 hours).

The query contract is the same as [Object Post](/en/blob-reference/endpoint/post), plus `filename`: there is no multipart envelope here, so the stored extension has to come from the query string. Uploading requires a paid plan.

<ParamField query="name" type="string" placeholder="File Name" required>
  A string representing the name of the file. (without extension)<br />Must adhere to the a to z, A to Z, 0 to 9, and \_ pattern. (3 to 32 characters)
</ParamField>

<ParamField query="filename" type="string" placeholder="Original filename">
  The original filename, extension included (e.g. `reads.fastq.gz`). The stored extension is derived from it, falling back to the `mime_type` parameter, then to `bin`.
</ParamField>

<ParamField query="prefix" type="string" placeholder="File Prefix">
  A string representing the prefix for the file.<br />Must adhere to the a to z, A to Z, 0 to 9, and \_ pattern. (3 to 32 characters)
</ParamField>

<ParamField query="expire" type="number" placeholder="Expiration (days)">
  A number indicating the expiration period of the file, ranging from 7 to 1825 days (5 years).
</ParamField>

<ParamField query="security_hash" type="boolean" placeholder="Security Hash">
  Set to true if a security hash is required.
</ParamField>

<ParamField query="auto_download" type="boolean" placeholder="Auto Download">
  Set to true if the file should be set for automatic download.
</ParamField>

### Limits

<Note>
  * Object size: up to **1 GiB** (1,073,741,824 bytes).
  * Chunk size: **5 MB minimum**, **32 MB maximum** (the last chunk may be smaller).
  * Chunks per object: **205** (part numbers run from 1 to 205).
  * Open uploads per account: **8** simultaneous (`TOO_MANY_OPEN_UPLOADS`, 429).
  * Rate limit: 5 opens per 10 seconds, blocked for 10 seconds past that.

  Read the limits from the `chunk` object in the response rather than hardcoding them.
</Note>

### Response

<ResponseField name="status" type="string">
  Indicates whether the call was successful. "success" if successful, "error" if not.
</ResponseField>

<ResponseField name="response" type="object">
  <Expandable title="Toggle object">
    <ResponseField name="upload" type="string">
      The opaque upload token. Carry it through every later call of the flow; it is the only handle to this upload.
    </ResponseField>

    <ResponseField name="id" type="string">
      The ID (key) the object will be stored under.
    </ResponseField>

    <ResponseField name="name" type="string">
      The name of the file.
    </ResponseField>

    <ResponseField name="prefix" type="string">
      The prefix under which the file will be stored (`null` when none was sent).
    </ResponseField>

    <ResponseField name="url" type="string">
      The public CDN URL the object will be served from once completed.
    </ResponseField>

    <ResponseField name="chunk" type="object">
      The chunked-flow limits: `min_size` and `max_size` (chunk bytes), `max_parts`, and `max_object_size` (total bytes).
    </ResponseField>
  </Expandable>
</ResponseField>

<RequestExample>
  ```bash cURL theme={null}
  curl --request POST \
    --url 'https://blob.squarecloud.app/v1/objects/chunked?name=myfile&filename=reads.fastq.gz&expire=30' \
    --header 'Authorization: YOUR_API_KEY'
  ```

  ```javascript JavaScript theme={null}
  const params = new URLSearchParams({
    name: 'myfile',
    filename: 'reads.fastq.gz',
    expire: '30',
  });

  const response = await fetch(`https://blob.squarecloud.app/v1/objects/chunked?${params}`, {
    method: 'POST',
    headers: { Authorization: 'YOUR_API_KEY' },
  });

  const { response: upload } = await response.json();
  // persist upload.upload — it is the only handle to this upload
  ```

  ```python Python theme={null}
  import requests

  response = requests.post(
      'https://blob.squarecloud.app/v1/objects/chunked',
      headers={'Authorization': 'YOUR_API_KEY'},
      params={'name': 'myfile', 'filename': 'reads.fastq.gz', 'expire': 30},
  )
  upload = response.json()['response']
  ```
</RequestExample>

<ResponseExample>
  ```json theme={null}
  {
    "status": "success",
    "response": {
      "upload": "MzE1NTU5NzE0NTY5ODk1OTM2NC9teWZpbGUtZXgzMC5mYXN0cS5negoyfjQ4WXcuLi4KMzA",
      "id": "3155597145698959364/myfile-ex30.fastq.gz",
      "name": "myfile",
      "prefix": null,
      "url": "https://public-blob.squarecloud.dev/3155597145698959364/myfile-ex30.fastq.gz",
      "chunk": {
        "min_size": 5242880,
        "max_size": 33554432,
        "max_parts": 205,
        "max_object_size": 1073741824
      }
    }
  }
  ```
</ResponseExample>

### Troubleshooting

<Tabs>
  <Tab title="400 Status Code">
    ### Object-Related

    <CodeGroup>
      ```json NAME theme={null}
      // The provided object name is invalid.
      // Must adhere to the a to z, A to Z, 0 to 9, and _ pattern.
      {
          "status": "error",
          "code": "INVALID_OBJECT_NAME"
      }
      ```

      ```json PREFIX theme={null}
      // The provided object prefix is invalid.
      // Must adhere to the a to z, A to Z, 0 to 9, and _ pattern.
      {
          "status": "error",
          "code": "INVALID_OBJECT_PREFIX"
      }
      ```

      ```json EXPIRE theme={null}
      // The provided expiration value for the object is invalid.
      // Must be a number ranging from 7 to 1825. (value in days).
      {
          "status": "error",
          "code": "INVALID_OBJECT_EXPIRE"
      }
      ```

      ```json FILETYPE theme={null}
      // The file extension is malformed or too long.
      {
          "status": "error",
          "code": "INVALID_FILE_TYPE"
      }
      ```

      ```json BLOCKED_FILE_TYPE theme={null}
      // Executable/installer extensions (exe, msi, bat, apk, ...) are not accepted.
      {
          "status": "error",
          "code": "BLOCKED_FILE_TYPE"
      }
      ```
    </CodeGroup>
  </Tab>

  <Tab title="401 Status Code">
    ### Unauthorized

    <CodeGroup>
      ```json ACCESS_DENIED theme={null}
      // The API key is missing or invalid. Set a valid key in the Authorization header.
      {
          "status": "error",
          "code": "ACCESS_DENIED"
      }
      ```

      ```json PERMISSION_DENIED theme={null}
      // The account has no active paid plan. Uploading to Blob Storage requires a paid plan.
      {
          "status": "error",
          "code": "PERMISSION_DENIED"
      }
      ```
    </CodeGroup>
  </Tab>

  <Tab title="403 Status Code">
    ### Storage quota exceeded

    <CodeGroup>
      ```json STORAGE_QUOTA_EXCEEDED theme={null}
      // You have exceeded your storage quota. Delete some files or upgrade your plan.
      {
          "status": "error",
          "code": "STORAGE_QUOTA_EXCEEDED"
      }
      ```
    </CodeGroup>
  </Tab>

  <Tab title="429 Status Code">
    ### Rate limited

    <CodeGroup>
      ```json RATE_LIMITED theme={null}
      // Init rate limit reached (5 opens per 10s window, blocked for 10s).
      {
          "status": "error",
          "code": "RATE_LIMITED"
      }
      ```

      ```json TOO_MANY_OPEN_UPLOADS theme={null}
      // 8 chunked uploads already open. Complete or abort one first.
      {
          "status": "error",
          "code": "TOO_MANY_OPEN_UPLOADS"
      }
      ```
    </CodeGroup>
  </Tab>

  <Tab title="500 Status Code">
    ### Upload failed

    <CodeGroup>
      ```json UPLOAD_FAILED theme={null}
      // Failed to open the chunked upload. Please try again later.
      {
          "status": "error",
          "code": "UPLOAD_FAILED"
      }
      ```
    </CodeGroup>
  </Tab>
</Tabs>