> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.reka.ai/vision/api-reference/v-2/youtube-websub-verify-v-2-youtube-websub-callback-get/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.reka.ai/_mcp/server.

# Youtube Websub Verify

GET https://vision-agent.api.reka.ai/v2/youtube-websub/callback

Echo hub.challenge so Google can confirm subscribe/unsubscribe.

This endpoint is unauthenticated by necessity, and both the callback URL
and YouTube channel ids are public, so every field here is attacker
controlled. A verification is only applied when it matches an operation we
actually requested against the topic we actually subscribed to.

Reference: https://docs.reka.ai/vision/api-reference/v-2/youtube-websub-verify-v-2-youtube-websub-callback-get

## Authentication

- `X-Api-Key` header (required) — API key authentication via X-Api-Key header
- `Authorization` header (bearer token, required) — Bearer token authentication via Authorization header

## Request

### Query parameters

- `hub.mode` (string, required)
- `hub.topic` (string, required)
- `hub.challenge` (string, optional, nullable)
- `hub.lease_seconds` (integer, optional, nullable)
- `hub.reason` (string, optional, nullable)

## Response

### 200

Successful Response

- `any`

## Examples

**SDK Code**

```python
import requests

url = "https://vision-agent.api.reka.ai/v2/youtube-websub/callback"

querystring = {"hub.mode":"hub.mode","hub.topic":"hub.topic"}

headers = {"X-Api-Key": "<apiKey>"}

response = requests.get(url, headers=headers, params=querystring)

print(response.json())
```

```javascript
const url = 'https://vision-agent.api.reka.ai/v2/youtube-websub/callback?hub.mode=hub.mode&hub.topic=hub.topic';
const options = {method: 'GET', headers: {'X-Api-Key': '<apiKey>'}};

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"
	"net/http"
	"io"
)

func main() {

	url := "https://vision-agent.api.reka.ai/v2/youtube-websub/callback?hub.mode=hub.mode&hub.topic=hub.topic"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("X-Api-Key", "<apiKey>")

	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://vision-agent.api.reka.ai/v2/youtube-websub/callback?hub.mode=hub.mode&hub.topic=hub.topic")

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

request = Net::HTTP::Get.new(url)
request["X-Api-Key"] = '<apiKey>'

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.get("https://vision-agent.api.reka.ai/v2/youtube-websub/callback?hub.mode=hub.mode&hub.topic=hub.topic")
  .header("X-Api-Key", "<apiKey>")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('GET', 'https://vision-agent.api.reka.ai/v2/youtube-websub/callback?hub.mode=hub.mode&hub.topic=hub.topic', [
  'headers' => [
    'X-Api-Key' => '<apiKey>',
  ],
]);

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

```csharp
using RestSharp;

var client = new RestClient("https://vision-agent.api.reka.ai/v2/youtube-websub/callback?hub.mode=hub.mode&hub.topic=hub.topic");
var request = new RestRequest(Method.GET);
request.AddHeader("X-Api-Key", "<apiKey>");
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = ["X-Api-Key": "<apiKey>"]

let request = NSMutableURLRequest(url: NSURL(string: "https://vision-agent.api.reka.ai/v2/youtube-websub/callback?hub.mode=hub.mode&hub.topic=hub.topic")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "GET"
request.allHTTPHeaderFields = headers

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()
```

> Documentation for Reka AI APIs.