Kling Audio API

Quick Start

Authentication

Add Authorization header with Bearer token to all requests:

Authorization: Bearer YOUR_API_KEY

Available Models

Pricing (up to 60% off)

Endpoints

Request Parameters

Sound Effects (kling-sound-effects)

Video-to-Audio (kling-video-to-audio)

Text-to-Speech (kling-tts)

Code Examples

curl -X POST https://api.apimodels.app/v1/audio/generations \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kling-sound-effects",
    "prompt": "Strong wind blowing through a forest with rustling leaves",
    "duration": "5.0"
  }'

Response Format

Create Task Response

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "clxxx...",
    "state": "pending",
    "model": "kling-audio/kling-sound-effects"
  }
}

Success Response

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "clxxx...",
    "state": "completed",
    "model": "kling-audio/kling-sound-effects",
    "resultUrls": ["https://...audio.mp3"],
    "createTime": 1705123450000,
    "completeTime": 1705123500000
  }
}

Failed Response

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "clxxx...",
    "state": "failed",
    "model": "kling-audio/kling-sound-effects",
    "failMsg": "Content policy violation"
  }
}

Webhook Callback (callback_url)

Pass callback_url in the create request. When the task reaches the completed or failed terminal state, our server sends a single HTTP POST to that URL with Content-Type: application/json (no signing header). Delivery is retried up to 3 times (exponential backoff 1s/2s/4s, 10s per attempt); if still unsuccessful, a background job keeps retrying for up to 30 minutes until your endpoint returns 2xx.

Payload Structure

POST {your callback_url}
Content-Type: application/json

{
  "code": 200,
  "msg": "success",
  "data": {
    "taskId": "clxxx...",
    "model": "kling-audio/kling-sound-effects",
    "state": "completed" | "failed",
    "param": "<JSON string>",            // request params, JSON.parse once
    "resultJson": "<JSON string> | null", // result object, JSON.parse once
    "failCode": null | "CONTENT_MODERATION | INVALID_INPUT | INSUFFICIENT_BALANCE | UPSTREAM_BUSY | UPSTREAM_FAILED | TIMEOUT | INTERNAL_ERROR | OTHER",
    "failMsg": null | "string",
    "retryable": true | false,           // present when state=failed: safe to retry/fallback
    "costTime": 12345,                    // duration in ms
    "completeTime": 1705123500000,        // ms epoch
    "createTime": 1705123450000           // ms epoch
  }
}

Note: data.param and data.resultJson are both JSON strings — call JSON.parse once on each.

Audio task: shape after JSON.parse(data.resultJson)

{
  "resultUrls":    ["https://r2.apimodels.app/audio/xxx.mp3"],
  "audioDuration": 12.5                // optional, seconds
}

resultUrls is an R2-hosted audio URL array (length 1 in success). audioDuration may be present (seconds). When state=failed, resultJson is typically null or {"resultUrls":[]}.

Node.js receiver example

app.post('/webhook/kling-audio', express.json(), (req, res) => {
  const { taskId, state, resultJson, failMsg } = req.body.data
  if (state === 'completed') {
    const r = JSON.parse(resultJson)
    console.log('audio ready', taskId, r.resultUrls[0], r.audioDuration)
  } else {
    console.warn('audio failed', taskId, failMsg)
  }
  res.status(200).end()                 // must be 2xx, otherwise we retry
})

Notes

• -A task stops retrying only after a 2xx response — once delivered it is never pushed again.
• -Callbacks are not signed today. Embed a random token in your callback_url path and verify it on receipt.
• -Use a public HTTPS endpoint that responds within 10 seconds (per-attempt timeout).

Task States

Error Codes

Important Notes

• *Audio files are stored for 30 days, download promptly
• *Text-to-audio supports duration from 3.0s to 10.0s
• *Video-to-audio requires video between 3-20 seconds
• *TTS supports max 1000 characters per request
• *For video-to-audio, provide either video_id or video_url
• *Poll every 5-10 seconds to check status