KuaishouTutorial

How to Use Kling 4.0 API

A step-by-step Kling 4.0 API tutorial with Node.js, Python and cURL: submit a text to video job, poll it or receive a webhook, and download the video. The example below costs $0.75.

Endpoints: 3; Text to Video · Image to Video · Reference to Video
Example request: $0.75; Text to Video
Languages: 3; Node.js · Python · cURL
Failed runs: $0; refunded automatically

Get API key Create with Kling 4.0 API docs

Get an API key

Create an account, add credits and create a key in Dashboard → API keys. Store it as CHEAPERGEN_API_KEY on your server. Every request sends it as a bearer token.

How to get a Kling 4.0 API key

Choose a Kling 4.0 endpoint

Each task has its own endpoint. All of them take a JSON body and return a generation you can poll.

Kling 4.0 API endpoints, required inputs and prices
Task	Endpoint	Required	From
Text to Video	kuaishou/kling-4.0/text-to-video	prompt	$0.1486/s
Image to Video	kuaishou/kling-4.0/image-to-video	prompt, image_url	$0.1486/s
Reference to Video	kuaishou/kling-4.0/reference-to-video	prompt	$0.1486/s

Submit a text to video job

This program submits the job, polls every 3 seconds until it finishes and prints the video URL. Swap the prompt and settings for your own.

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/text-to-video`, {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "A paper boat drifts along a rain-filled gutter at night, neon reflections, the soft patter of rain",
    "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/text-to-video", headers=headers, json={
    "prompt": "A paper boat drifts along a rain-filled gutter at night, neon reflections, the soft patter of rain",
    "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/text-to-video \
  -H "Authorization: Bearer $CHEAPERGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "prompt": "A paper boat drifts along a rain-filled gutter at night, neon reflections, the soft patter of rain",
  "aspect_ratio": "16:9",
  "resolution": "720p",
  "duration": 5
}'

Set the parameters that matter

The settings for kuaishou/kling-4.0/text-to-video, with what each one does to the price.

Kling 4.0 Text to Video parameters and their effect on price
Parameter	Type · default	What it does	Price effect
aspect_ratio	string (enum) · 16:9	Output frame shape. 16:9 · 9:16 · 1:1 · 21:9	Yes
resolution	string (enum) · 720p	Output resolution. Higher resolutions cost more per second. 720p · 1080p	720p: $0.1486/s 1080p: $0.2226/s
duration	integer · 5	Length of the generated clip in seconds (3–30s). You pay per second.	Billed per second

Other Kling 4.0 endpoints take the same shape with their own inputs:

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

{
  "prompt": "She turns toward the window and smiles as the curtains sway; slow push-in",
  "image_url": "https://cdn.cheapergen.com/samples/portrait.jpg",
  "resolution": "720p",
  "duration": 5
}

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

{
  "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
}

Get the result

A job moves from queued to running to succeeded, failed or canceled. Poll GET /api/v1/generations/{id}, or pass webhook_url and we POST the result to you. Download the output and store it yourself.

200 — succeeded

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "kuaishou/kling-4.0",
  "endpoint": "kuaishou/kling-4.0/text-to-video",
  "mode": "text-to-video",
  "status": "succeeded",
  "input": {
    "prompt": "A paper boat drifts along a rain-filled gutter at night, neon reflections, the soft patter of rain",
    "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"
}

Verify webhook signatures

Price a request before you run it

The quote endpoint is free and needs no key. It returns the price, the official price and your discount for exactly the input you send.

curl -X POST https://cheapergen.com/api/v1/quote/kuaishou/kling-4.0/text-to-video \
  -H "Content-Type: application/json" \
  -d '{"prompt":"A paper boat drifts along a rain-filled gutter at night, neon reflections, the soft patter of rain","aspect_ratio":"16:9","resolution":"720p","duration":5}'

API errors and what to do
Status	Code	Meaning
400	invalid_request	A parameter is missing or out of range — the message names it.
401	unauthorized	Missing, malformed or revoked API key.
402	insufficient_balance	Not enough credits for the quoted price; top up or enable auto top-up.
429	rate_limited	Too many requests or generations in progress; back off and retry.
502	upstream_error	The model failed; the hold is refunded and you can retry.
503	model_unavailable	No healthy route right now; retry later or pick another model.

Full Kling 4.0 API documentation

FAQ

Kling 4.0 API questions

No. The API is plain HTTPS with JSON, so the Node.js (fetch) and Python (requests) examples on this page are complete programs. Any language that can send an HTTP request works.

Yes. Add "webhook_url" to the request body and we POST the finished generation to it, signed with a CheaperGen-Signature header (HMAC-SHA256 of the timestamp and raw body). Polling GET /api/v1/generations/{id} works too.

Pass public URLs in "image_url", "end_image_url", "reference_image_urls", "reference_video_urls". Files without a public URL can be uploaded first with POST /api/v1/uploads, which returns a URL to use in the request.

Any whole number of seconds from 3 to 30, in one generation.

Text to Video starts at $0.1486/s; the example request on this page costs $0.75, 5% below the official price. Failed generations are refunded automatically.

How to Use Kling 4.0 API

Get an API key

Choose a Kling 4.0 endpoint

Submit a text to video job

Set the parameters that matter

Get the result

Price a request before you run it

Kling 4.0 API questions

Do I need an SDK to use the Kling 4.0 API?

Can I use a webhook instead of polling?

How do I send images or videos to the Kling 4.0 API?

How long can a video be?

What does a Kling 4.0 API call cost?