> ## Documentation Index
> Fetch the complete documentation index at: https://docs.crazyrouter.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Callback Protocol

> Webhook callback protocol for async tasks

> Last updated: 2026-06-06

## Overview

For async tasks (Midjourney image generation, video generation, music generation, etc.), Crazyrouter supports Webhook callbacks to notify task status changes.

## Callback URL Configuration

Specify the callback URL via the `notifyHook` parameter when submitting a task:

```json theme={null}
{
  "prompt": "a beautiful sunset",
  "notifyHook": "https://your-server.com/api/callback"
}
```

## Callback Request Format

Crazyrouter sends a POST request to your callback URL:

```
POST https://your-server.com/api/callback
Content-Type: application/json
```

### Midjourney Callback

```json theme={null}
{
  "id": "task_abc123",
  "action": "IMAGINE",
  "status": "SUCCESS",
  "prompt": "a beautiful sunset",
  "imageUrl": "https://cdn.example.com/image.png",
  "progress": "100%",
  "failReason": "",
  "submitTime": 1706000000000,
  "startTime": 1706000010000,
  "finishTime": 1706000060000
}
```

### Video Generation Callback (Kling/Luma/Runway)

```json theme={null}
{
  "id": "task_xyz789",
  "status": "succeed",
  "type": "video",
  "output": {
    "video_url": "https://cdn.example.com/video.mp4",
    "cover_url": "https://cdn.example.com/cover.jpg",
    "duration": 5.0
  },
  "created_at": 1706000000,
  "updated_at": 1706000120
}
```

### Suno Music Callback

```json theme={null}
{
  "id": "task_music456",
  "status": "complete",
  "output": {
    "audio_url": "https://cdn.example.com/song.mp3",
    "title": "My Song",
    "duration": 180
  }
}
```

## Callback Status Flow

```
Submitted → NOT_START → IN_PROGRESS → SUCCESS / FAILURE
```

A callback is triggered on each status change.

## Callback Server Examples

<CodeGroup>
  ```python Python (Flask) theme={null}
  from flask import Flask, request, jsonify

  app = Flask(__name__)

  @app.route("/api/callback", methods=["POST"])
  def callback():
      data = request.json
      task_id = data["id"]
      status = data["status"]

      print(f"Task {task_id} status update: {status}")

      if status == "SUCCESS":
          image_url = data.get("imageUrl")
          print(f"Image URL: {image_url}")

      return jsonify({"success": True})

  app.run(port=8080)
  ```

  ```javascript Node.js (Express) theme={null}
  const express = require('express');
  const app = express();
  app.use(express.json());

  app.post('/api/callback', (req, res) => {
    const { id, status, imageUrl } = req.body;
    console.log(`Task ${id} status: ${status}`);

    if (status === 'SUCCESS') {
      console.log(`Image: ${imageUrl}`);
    }

    res.json({ success: true });
  });

  app.listen(8080);
  ```
</CodeGroup>

<Warning>
  The callback URL must be publicly accessible. Ensure your server can receive POST requests and return a 200 status code within 5 seconds.
</Warning>

<Note>
  If a callback fails, the system retries up to 3 times with intervals of 10 seconds, 30 seconds, and 60 seconds.
</Note>