> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.simplified.com/api-reference/platform/assets/sign-asset-upload/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.simplified.com/_mcp/server.

# API · Assets · Sign a direct asset upload

POST https://api.simplified.com/api/v1/assets/sign
Content-Type: application/json

Start the same direct-to-storage upload flow used by Simplified's UI.
The client creates a UUID, calls this tool, then PUTs the local file bytes
directly to the returned `signed` URL using the declared MIME type and no
Simplified Authorization header. After the PUT succeeds, call
`registerAsset` with the returned metadata.


Reference: https://docs.simplified.com/api-reference/platform/assets/sign-asset-upload

## Authentication

- `Authorization` header (required) (prefixed with ` Api-Key   `) — Header authentication of the form `Api-Key  <token>`
- `Authorization` header (bearer token, required) — Bearer authentication of the form `Bearer <token>`, where token is your auth token.

## Request

### Body (application/json)

This endpoint expects a SignAssetUploadRequest.

- `filename` (string, required) — Original filename including extension.
- `filetype` (string, required) — MIME type, for example `image/png` or `video/mp4`.
- `resource` (enum, required, default: assets) — Storage resource namespace. Use `assets`.
  - Allowed values: `assets`
- `resource_id` (string, required) — Client-generated UUID that becomes the registered asset ID.

## Response

### 200

Signed upload URL and asset registration metadata

- `resource_id` (string, required)
- `asset` (string, required)
- `asset_url` (string, required)
- `signed` (string, required)
- `asset_key` (string, required)
- `asset_type` (integer, required)
- `bucket_name` (string, required)

## Errors

### 400 Bad Request Error

Invalid filename

- `any`

### 401 Unauthorized Error

Unauthorized

- `any`

## Examples

**Request**

```json
{
  "filename": "string",
  "filetype": "string",
  "resource": "assets",
  "resource_id": "string"
}
```

**Response**

```json
{
  "resource_id": "string",
  "asset": "string",
  "asset_url": "string",
  "signed": "string",
  "asset_key": "string",
  "asset_type": 1,
  "bucket_name": "string"
}
```

**SDK Code**

```python
import requests

url = "https://api.simplified.com/api/v1/assets/sign"

payload = {
    "filename": "string",
    "filetype": "string",
    "resource": "assets",
    "resource_id": "string"
}
headers = {
    "Authorization": "Api-Key  <apiKey>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.json())
```

```javascript
const url = 'https://api.simplified.com/api/v1/assets/sign';
const options = {
  method: 'POST',
  headers: {Authorization: 'Api-Key  <apiKey>', 'Content-Type': 'application/json'},
  body: '{"filename":"string","filetype":"string","resource":"assets","resource_id":"string"}'
};

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.simplified.com/api/v1/assets/sign"

	payload := strings.NewReader("{\n  \"filename\": \"string\",\n  \"filetype\": \"string\",\n  \"resource\": \"assets\",\n  \"resource_id\": \"string\"\n}")

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

	req.Header.Add("Authorization", "Api-Key  <apiKey>")
	req.Header.Add("Content-Type", "application/json")

	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.simplified.com/api/v1/assets/sign")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Api-Key  <apiKey>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"filename\": \"string\",\n  \"filetype\": \"string\",\n  \"resource\": \"assets\",\n  \"resource_id\": \"string\"\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.simplified.com/api/v1/assets/sign")
  .header("Authorization", "Api-Key  <apiKey>")
  .header("Content-Type", "application/json")
  .body("{\n  \"filename\": \"string\",\n  \"filetype\": \"string\",\n  \"resource\": \"assets\",\n  \"resource_id\": \"string\"\n}")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.simplified.com/api/v1/assets/sign', [
  'body' => '{
  "filename": "string",
  "filetype": "string",
  "resource": "assets",
  "resource_id": "string"
}',
  'headers' => [
    'Authorization' => 'Api-Key  <apiKey>',
    'Content-Type' => 'application/json',
  ],
]);

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

```csharp
using RestSharp;

var client = new RestClient("https://api.simplified.com/api/v1/assets/sign");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Api-Key  <apiKey>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"filename\": \"string\",\n  \"filetype\": \"string\",\n  \"resource\": \"assets\",\n  \"resource_id\": \"string\"\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "Authorization": "Api-Key  <apiKey>",
  "Content-Type": "application/json"
]
let parameters = [
  "filename": "string",
  "filetype": "string",
  "resource": "assets",
  "resource_id": "string"
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://api.simplified.com/api/v1/assets/sign")! 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()
```