Video Edit

Kling 4.0 changes an existing video as your prompt says, for example replacing an object or changing the style, optionally with reference images and reference videos.

Create a task

Use the shared create endpoint with model: "kling-4.0". It usually responds in under 1 second and the cost is frozen within a few seconds; the video usually takes 1–5 minutes. Get the result once the task has finished.

Headers

Body

Without duration

• Output length: the length of the video you edit (the longer of its video and audio tracks), rounded up to a whole second; less than 0.05 seconds over doesn't count (10.02 s gives 10 seconds, 10.06 s gives 11).
• Billing: 30 × the price per second is frozen first; when the task succeeds, the actual output length is charged and the rest returned, see Pricing.
• Balance: your available balance must cover the 30 seconds (and so must the key's spend limits), even if the video is shorter; otherwise the task fails with insufficient_balance (or spend_limit_exceeded). Send duration to freeze only what you ask for.

Replace the car with the one in the reference image, 1080p, 8 seconds:

curl https://api.nanoapi.ai/v1/tasks \
  -H "Authorization: Bearer $NANOAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kling-4.0",
    "mode": "video_edit",
    "video_url": "https://example.com/source.mp4",
    "image_urls": ["https://example.com/ref.jpg"],
    "prompt": "Replace the car with the one in the reference image",
    "aspect_ratio": "auto",
    "resolution": "1080p",
    "duration": 8
  }'

With a reference video and no duration (the output follows the video you edit), 720p:

curl https://api.nanoapi.ai/v1/tasks \
  -H "Authorization: Bearer $NANOAPI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "kling-4.0",
    "mode": "video_edit",
    "video_url": "https://example.com/main.mp4",
    "video_urls": ["https://example.com/dance.mp4"],
    "prompt": "Edit @Video1: make her move like the dancer in @Video2",
    "aspect_ratio": "auto",
    "resolution": "720p"
  }'

Response: 200 OK. data is the newly created task, with only these fields; each one is described in Create a task: Response. Keep data.id to get the result: once the task succeeds, the video is at data.outputs[0].url of the retrieved task or the webhook. The task can still fail after it's created (for example a file can't be downloaded), so go by what retrieving the task or the webhook tells you.

{
  "code": 200,
  "message": "success",
  "data": {
    "object": "task",
    "id": "tk_01jbc4k7m2n9p5q8r3s6t1v4w7",
    "model": "kling-4.0",
    "status": "queued",
    "error": null,
    "created_at": "2026-10-30T08:30:00Z"
  }
}

Pricing

cost = duration × price per second of the resolution

Loading the current prices…

Example: 1080p for 8 seconds (the first request above) costs 8 × the 1080p price per second.

Without duration (the second request above), 30 × the 720p price per second is frozen first. When the task succeeds, the output length × the price per second is charged and the rest returned: for an 11-second video, 11 seconds are charged and 19 returned. billing.billed_seconds is then the output length. If the task fails, all of it is returned.

Billed seconds are the duration you ask for, however long the video you edit is; without duration, the output length. Prices change, so read the current ones from GET /v1/products (the prices rows whose mode is this mode) instead of hard-coding them; billing.frozen on the retrieved task is what counts. All Kling 4.0 prices: Kling 4.0 → Pricing.

Errors

Create request errors: the request fails with an HTTP error and no task is created. Specific to this mode:

Other errors of the create endpoint (401, 402, 429 and so on): Create a task → Errors.

Task failures: the create request succeeded (200) and the task later turned failed. There's no HTTP status: the reason is the task's error.type, from retrieving the task or the webhook.

Failure reasons shared by every mode (such as a balance too low for the task): Kling 4.0 → Errors; all of them: Failure reasons.