> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://platform.bctrl.ai/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://platform.bctrl.ai/_mcp/server.

# Upload a file

POST https://api.bctrl.ai/v1/files
Content-Type: multipart/form-data

Upload a file into a space and return the canonical file resource.

Reference: https://platform.bctrl.ai/api/api-reference/files/upload

## Authentication

- `Authorization` header (bearer token, required) — Use Bearer \<api-key>.

## Servers

- `https://api.bctrl.ai` (Production, default)
- `http://localhost:8787` (Local development gateway)

## Request

### Query parameters

- `spaceId` (string, optional) — Filter by a prefixed space ID, or pass `default` to use the caller default space.

### Headers

- `BCTRL-Subaccount-Id` (string, optional) — Optional effective subaccount context for organization API keys. Subaccount API keys are already scoped and cannot use this header to act as another subaccount.

### Body (multipart/form-data)

- `file` (file, required) — File bytes to upload.
- `metadata` (string, optional) — Optional JSON object string with caller-owned file metadata.
- `name` (string, optional) — Optional display filename.
- `path` (string, optional) — Optional relative destination path. Must not be absolute or contain . or .. path segments.

## Response

### 201

Created

- `contentType` (string, required)
- `createdAt` (datetime, required) — RFC 3339 timestamp with a UTC offset.
- `downloadUrl` (string, required)
- `id` (string, required) — Unique file identifier generated by BCTRL.
- `name` (string, required) — Customer-facing resource name. 1–200 characters.
- `path` (string, required)
- `sizeBytes` (integer, required) — Non-negative number of bytes.
- `source` (enum, required)
  - Allowed values: `upload`, `runtime`
- `spaceId` (string, required) — Unique space identifier generated by BCTRL.
- `expiresAt` (datetime, optional) — RFC 3339 timestamp with a UTC offset.
- `metadata` (object, optional, nullable)
- `runId` (string, optional) — Unique run identifier generated by BCTRL.
- `runtimeId` (string, optional) — Unique runtime identifier generated by BCTRL.
- `type` (string, optional)

## Examples

**Request**

```json
{
  "file": "<file: string>"
}
```

**Response**

```json
{
  "contentType": "string",
  "createdAt": "2026-07-26T12:00:00Z",
  "downloadUrl": "string",
  "id": "file_AAAAAAAAAAAAAAAAAAAAAA",
  "name": "Production browser",
  "path": "string",
  "sizeBytes": 1024,
  "source": "upload",
  "spaceId": "sp_AAAAAAAAAAAAAAAAAAAAAA",
  "expiresAt": "2026-07-26T12:00:00Z",
  "metadata": {},
  "runId": "run_AAAAAAAAAAAAAAAAAAAAAA",
  "runtimeId": "rt_AAAAAAAAAAAAAAAAAAAAAA",
  "type": "string"
}
```

**SDK Code**

```python
import requests

url = "https://api.bctrl.ai/v1/files"

files = { "file": "open('string', 'rb')" }
payload = {
    "metadata": ,
    "name": ,
    "path": 
}
headers = {"Authorization": "Bearer <token>"}

response = requests.post(url, data=payload, files=files, headers=headers)

print(response.json())
```

```javascript
const url = 'https://api.bctrl.ai/v1/files';
const form = new FormData();
form.append('file', 'string');
form.append('metadata', '');
form.append('name', '');
form.append('path', '');

const options = {method: 'POST', headers: {Authorization: 'Bearer <token>'}};

options.body = form;

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.bctrl.ai/v1/files"

	payload := strings.NewReader("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"string\"\r\nContent-Type: application/octet-stream\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"metadata\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"name\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"path\"\r\n\r\n\r\n-----011000010111000001101001--\r\n")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://api.bctrl.ai/v1/files")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request.body = "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"string\"\r\nContent-Type: application/octet-stream\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"metadata\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"name\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"path\"\r\n\r\n\r\n-----011000010111000001101001--\r\n"

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.bctrl.ai/v1/files")
  .header("Authorization", "Bearer <token>")
  .body("-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"string\"\r\nContent-Type: application/octet-stream\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"metadata\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"name\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"path\"\r\n\r\n\r\n-----011000010111000001101001--\r\n")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.bctrl.ai/v1/files', [
  'multipart' => [
    [
        'name' => 'file',
        'filename' => 'string',
        'contents' => null
    ]
  ]
  'headers' => [
    'Authorization' => 'Bearer <token>',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.bctrl.ai/v1/files");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
request.AddParameter("undefined", "-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"file\"; filename=\"string\"\r\nContent-Type: application/octet-stream\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"metadata\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"name\"\r\n\r\n\r\n-----011000010111000001101001\r\nContent-Disposition: form-data; name=\"path\"\r\n\r\n\r\n-----011000010111000001101001--\r\n", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = ["Authorization": "Bearer <token>"]
let parameters = [
  [
    "name": "file",
    "fileName": "string"
  ],
  [
    "name": "metadata",
    "value": 
  ],
  [
    "name": "name",
    "value": 
  ],
  [
    "name": "path",
    "value": 
  ]
]

let boundary = "---011000010111000001101001"

var body = ""
var error: NSError? = nil
for param in parameters {
  let paramName = param["name"]!
  body += "--\(boundary)\r\n"
  body += "Content-Disposition:form-data; name=\"\(paramName)\""
  if let filename = param["fileName"] {
    let contentType = param["content-type"]!
    let fileContent = String(contentsOfFile: filename, encoding: String.Encoding.utf8)
    if (error != nil) {
      print(error as Any)
    }
    body += "; filename=\"\(filename)\"\r\n"
    body += "Content-Type: \(contentType)\r\n\r\n"
    body += fileContent
  } else if let paramValue = param["value"] {
    body += "\r\n\r\n\(paramValue)"
  }
}

let request = NSMutableURLRequest(url: NSURL(string: "https://api.bctrl.ai/v1/files")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```