When you submit an instrumental generation task to the Suno API using the /api/v1/generate/add-instrumental endpoint, you can use the callBackUrl parameter to set a callback URL. The system will automatically push the results to your specified address when the task is completed. This callback is triggered by the following API endpoint:

Add Instrumental API

POST /api/v1/generate/add-instrumental - Generate instrumental accompaniment based on uploaded audio files

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Callback Mechanism Overview

The callback mechanism eliminates the need to poll the API for task status. The system will proactively push task completion results to your server.

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Callback Timing

The system will send callback notifications in the following situations:
  • Text generation completed (callbackType: “text”)
  • First audio track generation completed (callbackType: “first”)
  • All audio tracks generation completed (callbackType: “complete”)
  • Instrumental generation task failed
  • Errors occurred during task processing

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Callback Method

  • HTTP Method: POST
  • Content Type: application/json
  • Timeout Setting: 15 seconds

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Callback Request Format

When the task progresses or completes, the system will send a POST request to your callBackUrl in the following format: 
{
  "code": 200,
  "msg": "All generated successfully.",
  "data": {
    "callbackType": "complete",
    "task_id": "2fac****9f72",
    "data": [
      {
        "id": "8551****662c",
        "audio_url": "https://example.cn/****.mp3",
        "stream_audio_url": "https://example.cn/****",
        "image_url": "https://example.cn/****.jpeg",
        "prompt": "[Verse] Night city lights shining bright",
        "model_name": "chirp-v4-5",
        "title": "Iron Man",
        "tags": "electrifying, rock",
        "createTime": "2025-01-01 00:00:00",
        "duration": 198.44
      }
    ]
  }
}

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Status Code Description

Status CodeDescription
200Success - Request has been processed successfully
400Validation Error - Lyrics contained copyrighted material
408Rate Limited - Timeout
413Conflict - Uploaded audio matches existing work of art
500Server Error - An unexpected error occurred while processing the request
501Audio generation failed
531Server Error - Sorry, the generation failed due to an issue. Your credits have been refunded. Please try again

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Callback Reception Examples

Here are example codes for receiving callbacks in popular programming languages: 
const express = require('express');
const app = express();

app.use(express.json());

app.post('/instrumental-callback', (req, res) => {
  const { code, msg, data } = req.body;
  
  console.log('Received instrumental callback:', {
    taskId: data.task_id,
    status: code,
    message: msg,
    callbackType: data.callbackType
  });
  
  if (code === 200) {
    // Task completed successfully
    if (data.callbackType === 'complete') {
      console.log('Instrumental generation completed:', data.data);
      
      // Process generated instrumental data
      data.data.forEach(audio => {
        console.log(`Audio ID: ${audio.id}`);
        console.log(`Audio URL: ${audio.audio_url}`);
        console.log(`Title: ${audio.title}`);
        console.log(`Duration: ${audio.duration} seconds`);
      });
      
    } else if (data.callbackType === 'first') {
      console.log('First track completed');
      
    } else if (data.callbackType === 'text') {
      console.log('Text generation completed');
    }
    
  } else {
    // Task failed
    console.log('Task failed:', msg);
  }
  
  // Return 200 status code to confirm callback received
  res.status(200).json({ status: 'received' });
});

app.listen(3000, () => {
  console.log('Instrumental callback server running on port 3000');
});

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Best Practices

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Callback URL Configuration Recommendations

  1. Use HTTPS: Ensure your callback URL uses HTTPS protocol for secure data transmission
  2. Verify Source: Verify the legitimacy of the request source in callback processing
  3. Idempotent Processing: The same task_id may receive multiple callbacks, ensure processing logic is idempotent
  4. Quick Response: Callback processing should return a 200 status code as quickly as possible to avoid timeout
  5. Asynchronous Processing: Complex business logic should be processed asynchronously to avoid blocking callback response
  6. Stage Tracking: Differentiate between different generation stages based on callbackType and arrange business logic appropriately

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Important Reminders

  • Callback URL must be a publicly accessible address
  • Server must respond within 15 seconds, otherwise it will be considered a timeout
  • If 3 consecutive retries fail, the system will stop sending callbacks
  • Please ensure the stability of callback processing logic to avoid callback failures due to exceptions
  • Pay attention to handling different callbackType callbacks, especially the complete type for final results

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Alternative Solution

If you cannot use the callback mechanism, you can also use polling:

Poll Query Results

Use the get music details endpoint to regularly query task status. We recommend querying every 30 seconds.