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Kling 4.0 Reference to Video API

Name: Kling 4.0 API
Brand: Kuaishou
SKU: kuaishou/kling-4.0
Availability: InStock

Reference to Video with Kling 4.0 by Kuaishou. Kling's newest video model — up to 30 s with stereo sound on every clip.

kuaishou/kling-4.0/reference-to-video

FromUp to −5%

$0.149/s$0.157

per second of video · 720p

Operational99.92% uptime (30 days)median 6m 44s

Create with Kling 4.0 Get API key

API docs →Compare models →

Try Kling 4.0 Reference to Video

Prompt*

Type @ to point at a reference image or video0/8000

Reference images

Up to 10 images for characters, products, style or scene. Refer to them in the prompt as @Image1, @Image2…

Reference videos

Up to 5 MP4/MOV clips for motion, camera moves or effects (3–30 s each, 30 s in total, ≤ 200 MB each). Refer to them as @Video1, @Video2… With a reference video, the output seconds plus the longer of the output and the reference videos are billed at a lower per-second rate.

Aspect ratio

Output frame shape.

Resolution

Output resolution. Higher resolutions cost more per second.

Duration

Length of the generated clip in seconds (3–30s). You pay per second.

Estimated cost…

Create a free account with Google or email — pay only for what you generate.

Your video will appear here

Write a prompt, pick your settings and hit Run. You only pay for successful generations.

Also available: Kling 4.0 Text to Video · Kling 4.0 Image to Video

See the Kling 4.0 examples and prompts

Kling 4.0 Reference to Video API

POST/api/v1/run/kuaishou/kling-4.0/reference-to-video

Submits an asynchronous job and returns 202 with a generation id. Poll GET /api/v1/generations/{id} or pass webhook_url. See job lifecycle.

Input parameters

Name	Type	Description	Affects price
`prompt`required	string	Describe the shot: subject, action, camera movement, lighting and style.	No
`reference_image_urls`	string[] (URLs)	Up to 10 images for characters, products, style or scene. Refer to them in the prompt as @Image1, @Image2… Max items: 10	No
`reference_video_urls`	string[] (video URLs)	Up to 5 MP4/MOV clips for motion, camera moves or effects (3–30 s each, 30 s in total, ≤ 200 MB each). Refer to them as @Video1, @Video2… With a reference video, the output seconds plus the longer of the output and the reference videos are billed at a lower per-second rate. Max items: 5	Yes
`aspect_ratio`	string (enum)	Output frame shape. Values: 16:9 · 9:16 · 1:1 · 21:9 Default: 16:9	Yes
`resolution`	string (enum)	Output resolution. Higher resolutions cost more per second. Values: 720p · 1080p Default: 720p	Yes
`duration`	integer	Length of the generated clip in seconds (3–30s). You pay per second. Range: 3–30s Default: 5	Yes
`webhook_url`	string (URL)	Optional. We POST the finished generation here, signed with your webhook secret. Webhooks	No

Request

const API = "https://cheapergen.com/api/v1";
const headers = {
  Authorization: `Bearer ${process.env.CHEAPERGEN_API_KEY}`,
  "Content-Type": "application/json",
};

// 1. Submit the job
let job = await fetch(`${API}/run/kuaishou/kling-4.0/reference-to-video`, {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "@Image1 walks along the beach at sunset, following the camera move of @Video1",
    "reference_image_urls": [
      "https://cdn.cheapergen.com/samples/reference-1.jpg"
    ],
    "reference_video_urls": [
      "https://cdn.cheapergen.com/samples/reference-1.mp4"
    ],
    "aspect_ratio": "16:9",
    "resolution": "720p",
    "duration": 5
  }),
}).then((r) => r.json());

// 2. Poll until it finishes (or pass webhook_url and skip polling)
while (job.status === "queued" || job.status === "running") {
  await new Promise((r) => setTimeout(r, 3000));
  job = await fetch(`${API}/generations/${job.id}`, { headers }).then((r) => r.json());
}

console.log(job.status === "succeeded" ? job.output.video.url : job.error);

import os, time, requests

API = "https://cheapergen.com/api/v1"
headers = {"Authorization": f"Bearer {os.environ['CHEAPERGEN_API_KEY']}"}

# 1. Submit the job
job = requests.post(f"{API}/run/kuaishou/kling-4.0/reference-to-video", headers=headers, json={
    "prompt": "@Image1 walks along the beach at sunset, following the camera move of @Video1",
    "reference_image_urls": [
        "https://cdn.cheapergen.com/samples/reference-1.jpg"
    ],
    "reference_video_urls": [
        "https://cdn.cheapergen.com/samples/reference-1.mp4"
    ],
    "aspect_ratio": "16:9",
    "resolution": "720p",
    "duration": 5
}).json()

# 2. Poll until it finishes (or pass "webhook_url" and skip polling)
while job["status"] in ("queued", "running"):
    time.sleep(3)
    job = requests.get(f"{API}/generations/{job['id']}", headers=headers).json()

print(job["status"], job["output"]["video"]["url"] if job["status"] == "succeeded" else job["error"])

curl -X POST https://cheapergen.com/api/v1/run/kuaishou/kling-4.0/reference-to-video \
  -H "Authorization: Bearer $CHEAPERGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "prompt": "@Image1 walks along the beach at sunset, following the camera move of @Video1",
  "reference_image_urls": [
    "https://cdn.cheapergen.com/samples/reference-1.jpg"
  ],
  "reference_video_urls": [
    "https://cdn.cheapergen.com/samples/reference-1.mp4"
  ],
  "aspect_ratio": "16:9",
  "resolution": "720p",
  "duration": 5
}'

Response

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "kuaishou/kling-4.0",
  "endpoint": "kuaishou/kling-4.0/reference-to-video",
  "mode": "reference-to-video",
  "status": "queued",
  "input": {
    "prompt": "@Image1 walks along the beach at sunset, following the camera move of @Video1",
    "reference_image_urls": [
      "https://cdn.cheapergen.com/samples/reference-1.jpg"
    ],
    "reference_video_urls": [
      "https://cdn.cheapergen.com/samples/reference-1.mp4"
    ],
    "aspect_ratio": "16:9",
    "resolution": "720p",
    "duration": 5
  },
  "output": null,
  "error": null,
  "cost": {
    "amount_usd": 0.2255,
    "currency": "usd",
    "estimated": true,
    "official_usd": null,
    "list_price_source": "official",
    "list_price_label": "Official",
    "saved_usd": null
  },
  "source": "api",
  "started_at": null,
  "completed_at": null,
  "urls": {
    "get": "https://cheapergen.com/api/v1/generations/gen_8c2QmX1nq0k4",
    "cancel": "https://cheapergen.com/api/v1/generations/gen_8c2QmX1nq0k4/cancel"
  },
  "created_at": "2026-10-15T09:21:04Z"
}

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "kuaishou/kling-4.0",
  "endpoint": "kuaishou/kling-4.0/reference-to-video",
  "mode": "reference-to-video",
  "status": "succeeded",
  "input": {
    "prompt": "@Image1 walks along the beach at sunset, following the camera move of @Video1",
    "reference_image_urls": [
      "https://cdn.cheapergen.com/samples/reference-1.jpg"
    ],
    "reference_video_urls": [
      "https://cdn.cheapergen.com/samples/reference-1.mp4"
    ],
    "aspect_ratio": "16:9",
    "resolution": "720p",
    "duration": 5
  },
  "output": {
    "video": {
      "url": "https://cdn.cheapergen.com/outputs/gen_8c2Q.mp4",
      "content_type": "video/mp4"
    }
  },
  "error": null,
  "cost": {
    "amount_usd": 0.2255,
    "currency": "usd",
    "estimated": false,
    "official_usd": 0.264,
    "list_price_source": "official",
    "list_price_label": "Official",
    "saved_usd": 0.0385
  },
  "source": "api",
  "created_at": "2026-10-15T09:21:04Z",
  "started_at": "2026-10-15T09:21:06Z",
  "completed_at": "2026-10-15T09:22:31Z"
}

Kling 4.0 pricing

Pay per second of video as you go, with no subscription required (monthly plans are optional). Failed generations are refunded automatically.

Tier	Official price	CheaperGen	You save
720p audio included	~~$0.157~~/s	$0.1486/s	−5%
1080p audio included	~~$0.235~~/s	$0.2226/s	−5%

Official price: Kling developer API list price for Kling 4.0, kling.ai/dev/pricing (1 unit = $0.157 / s at 720p, 1.5 units = $0.235 / s at 1080p; with input video $0.094 / $0.141 per second of output plus the longer of the output and the input video; audio always on). Prices verified October 18, 2026.
Audio is always generated and included in the price.
With a reference video, the output seconds plus the longer of the output and the reference videos are billed at a lower per-second rate.