> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Get avatar upload URL

POST https://api.smallest.ai/atoms/v1/agent/{id}/avatar/presigned-url
Content-Type: application/json

Generates a pre-signed S3 upload URL for the agent's widget avatar image. Upload the image directly to S3 using the returned `presignedUrl`, then save `cdnUrl` as the agent's avatar via `PATCH /agent/{id}/widget-config`.

Reference: https://docs.smallest.ai/voice-agents/api-reference/widget/get-agent-avatar-presigned-url

## Authentication

- `Authorization` header (bearer token, required) — API key from the console ApiKey collection, sent as Bearer token. Also accepts session cookies for browser-based auth.

## Request

### Path parameters

- `id` (string, required) — Agent ObjectId

### Body (application/json)

- `fileName` (string, required) — Original file name (used to construct the S3 key)
- `contentType` (string, required) — MIME type. Must start with `image/`
- `fileSize` (double, required) — File size in bytes. Must be greater than 0 and at most 2 MB (2,097,152 bytes)

## Response

### 200

Pre-signed upload URL and CDN URL

- `success` (boolean, optional)
- `data` (object, optional)
  - `presignedUrl` (string, optional) — S3 pre-signed PUT URL (expires in 300 s)
  - `cdnUrl` (string, optional) — Final public CDN URL to save on the agent after upload
  - `key` (string, optional) — S3 object key

## Examples

**Request**

```json
{
  "fileName": "string",
  "contentType": "string",
  "fileSize": 1.1
}
```

**Response**

```json
{
  "success": true,
  "data": {
    "presignedUrl": "string",
    "cdnUrl": "string",
    "key": "string"
  }
}
```

**SDK Code**

```python
import requests

url = "https://api.smallest.ai/atoms/v1/agent/id/avatar/presigned-url"

payload = {
    "fileName": "string",
    "contentType": "string",
    "fileSize": 1.1
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.json())
```

```javascript
const url = 'https://api.smallest.ai/atoms/v1/agent/id/avatar/presigned-url';
const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: '{"fileName":"string","contentType":"string","fileSize":1.1}'
};

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.smallest.ai/atoms/v1/agent/id/avatar/presigned-url"

	payload := strings.NewReader("{\n  \"fileName\": \"string\",\n  \"contentType\": \"string\",\n  \"fileSize\": 1.1\n}")

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

	req.Header.Add("Authorization", "Bearer <token>")
	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.smallest.ai/atoms/v1/agent/id/avatar/presigned-url")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"fileName\": \"string\",\n  \"contentType\": \"string\",\n  \"fileSize\": 1.1\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.smallest.ai/atoms/v1/agent/id/avatar/presigned-url")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"fileName\": \"string\",\n  \"contentType\": \"string\",\n  \"fileSize\": 1.1\n}")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.smallest.ai/atoms/v1/agent/id/avatar/presigned-url', [
  'body' => '{
  "fileName": "string",
  "contentType": "string",
  "fileSize": 1.1
}',
  'headers' => [
    'Authorization' => 'Bearer <token>',
    'Content-Type' => 'application/json',
  ],
]);

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

```csharp
using RestSharp;

var client = new RestClient("https://api.smallest.ai/atoms/v1/agent/id/avatar/presigned-url");
var request = new RestRequest(Method.POST);
request.AddHeader("Authorization", "Bearer <token>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"fileName\": \"string\",\n  \"contentType\": \"string\",\n  \"fileSize\": 1.1\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "Authorization": "Bearer <token>",
  "Content-Type": "application/json"
]
let parameters = [
  "fileName": "string",
  "contentType": "string",
  "fileSize": 1.1
] as [String : Any]

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

let request = NSMutableURLRequest(url: NSURL(string: "https://api.smallest.ai/atoms/v1/agent/id/avatar/presigned-url")! 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()
```