> For the complete documentation index, see [llms.txt](https://docs.release.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.release.com/reference-documentation/release-api/ai-sandbox-api/file-uploads.md).

# File Uploads

The File Uploads API provides a presigned-URL workflow for uploading files that can be attached to sandbox sessions as resources. Uploads are limited to 100 MB per file.

To obtain your authentication credentials, [install the Release CLI](/cli/installation.md) and run `release auth login`. The CLI stores credentials in `~/.release.yaml`.

***

## Upload Flow

Uploading a file to a sandbox session is a two-step process:

1. **Get a presigned URL** — POST to the endpoint below with the file metadata. The response contains a `presigned_url` and an `s3_uri`.
2. **PUT the file content** — Send a `PUT` request to the `presigned_url` with the raw file bytes as the request body. Set the `Content-Type` header to the same MIME type you provided in step 1.

Once uploaded, reference the file in a session by using the `s3_uri` value when creating a session resource of type `file` (see [Session Resources](/reference-documentation/release-api/ai-sandbox-api/sessions.md#resource-types)).

***

## Get Presigned Upload URL

Returns a presigned S3 URL that you can PUT file content to, along with an S3 URI for referencing the uploaded file in session resources.

#### Endpoint

<mark style="color:green;">`POST`</mark> `https://backend-{handle}-envs.gcp.release.com/ai/accounts/{accountId}/sandbox_uploads`

#### Authentication

Authenticate using headers from your `~/.release.yaml` file. To set this up, [install the Release CLI](/cli/installation.md) and run `release auth login`.

| Header       | Description                                       |
| ------------ | ------------------------------------------------- |
| X-User-Email | User email from `~/.release.yaml` (`login` field) |
| X-User-Token | User token from `~/.release.yaml` (`token` field) |

#### Headers

| Header       | Value              |
| ------------ | ------------------ |
| Content-Type | `application/json` |
| Accept       | `application/json` |

#### Path Parameters

| Name      | Type            | Required | Description            |
| --------- | --------------- | -------- | ---------------------- |
| accountId | string (hashid) | Yes      | The Release account ID |

#### Request Body

| Field         | Type    | Required | Description                                                  |
| ------------- | ------- | -------- | ------------------------------------------------------------ |
| filename      | string  | Yes      | Name of the file to upload                                   |
| content\_type | string  | Yes      | MIME type of the file (e.g. `text/plain`, `application/zip`) |
| size\_bytes   | integer | Yes      | File size in bytes (maximum 100 MB)                          |

**Example**

```json
{
  "filename": "data.txt",
  "content_type": "text/plain",
  "size_bytes": 1024
}
```

#### Status Codes

| Code | Description                                   |
| ---- | --------------------------------------------- |
| 201  | Presigned URL generated                       |
| 401  | Unauthorized — invalid or missing credentials |
| 422  | Validation error (see error codes below)      |

#### Error Codes

| Code                | Description                                          |
| ------------------- | ---------------------------------------------------- |
| file\_too\_large    | File exceeds the 100 MB size limit                   |
| no\_upload\_cluster | No cluster is configured for uploads on this account |

#### Response Body

| Field               | Type   | Description                                                        |
| ------------------- | ------ | ------------------------------------------------------------------ |
| data.presigned\_url | string | URL to PUT the file content to                                     |
| data.s3\_uri        | string | S3 URI to reference when creating session resources of type `file` |

#### Example Responses

**201 Created**

```json
{
  "data": {
    "presigned_url": "https://s3.amazonaws.com/bucket/path?...",
    "s3_uri": "s3://bucket/path"
  }
}
```

**422 File Too Large**

```json
{
  "errors": [
    {
      "code": "file_too_large",
      "message": "File exceeds the 100 MB size limit"
    }
  ]
}
```

**422 No Upload Cluster**

```json
{
  "errors": [
    {
      "code": "no_upload_cluster",
      "message": "No cluster configured for uploads"
    }
  ]
}
```


---

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