POST
/
api
/
v1
/
generate
/
upload-extend
Upload And Extend Audio
curl --request POST \
  --url https://api.sunoapi.org/api/v1/generate/upload-extend \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "uploadUrl": "https://storage.example.com/upload",
  "defaultParamFlag": true,
  "instrumental": true,
  "prompt": "Extend the music with more relaxing notes",
  "style": "Classical",
  "title": "Peaceful Piano Extended",
  "continueAt": 60,
  "model": "V3_5",
  "negativeTags": "Relaxing Piano",
  "vocalGender": "m",
  "styleWeight": 0.65,
  "weirdnessConstraint": 0.65,
  "audioWeight": 0.65,
  "callBackUrl": "https://api.example.com/callback"
}'
{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "5c79****be8e"
  }
}

​
Parameter Usage Guide

  • When defaultParamFlag is true (Custom Parameters):
    • If instrumental is true: style, title, and uploadUrl are required
    • If instrumental is false: style, prompt, title, and uploadUrl are required
    • prompt length limit by model:
      • V3_5 & V4: Maximum 3000 characters
      • V4_5 & V4_5PLUS: Maximum 5000 characters
    • style length limit by model:
      • V3_5 & V4: Maximum 200 characters
      • V4_5 & V4_5PLUS: Maximum 1000 characters
    • title length limit by model:
      • V3_5 & V4: Maximum 80 characters
      • V4_5 & V4_5PLUS: Maximum 100 characters
    • continueAt: the time point in seconds from which to start extending (must be greater than 0 and less than the uploaded audio duration)
    • uploadUrl: specifies the upload location for audio files; ensure uploaded audio does not exceed 8 minutes.
  • When defaultParamFlag is false (Default Parameters):
    • Regardless of instrumental setting, only uploadUrl and prompt are required
    • Other parameters will use the original audio’s parameters

​
Developer Notes

  1. Generated files will be retained for 14 days
  2. Model version must be consistent with the source music
  3. This feature is ideal for creating longer works by extending existing music
  4. uploadUrl parameter specifies the upload location for audio files; provide a valid URL.

Authorizations

​
Authorization
string
header
required

🔑 API Authentication

All endpoints require authentication using Bearer Token.

Get API Key

  1. Visit the API Key Management Page to obtain your API Key

Usage

Add to request headers:

Authorization: Bearer YOUR_API_KEY

⚠️ Note:

  • Keep your API Key secure and do not share it with others
  • If you suspect your API Key has been compromised, reset it immediately from the management page

Body

application/json

Response

Request successful

The response is of type object.