Kling 4.0 API documentation

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

Everything you need to call Kling 4.0 from your code. Base URL https://cheapergen.com/api/v1. Try it first in the playground.

Using a coding agent?

Paste this into Claude Code, Cursor, Codex or any coding agent. It adds the API to your project, keeps the key in CHEAPERGEN_API_KEY and tests with a free quote before anything is spent.

Add Kling 4.0 (CheaperGen endpoint kuaishou/kling-4.0/text-to-video) to this project by following https://cheapergen.com/agents/integrate.md

What your agent reads

Authentication

Create a key in Dashboard → API keys and send it as a bearer token. Keep keys server-side.

export CHEAPERGEN_API_KEY="cg_live_…"

# every request
Authorization: Bearer $CHEAPERGEN_API_KEY

Kling 4.0 Text to Video API

POST/api/v1/run/kuaishou/kling-4.0/text-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
`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/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
}'

Response

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "kuaishou/kling-4.0",
  "endpoint": "kuaishou/kling-4.0/text-to-video",
  "mode": "text-to-video",
  "status": "queued",
  "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": 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/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"
}

Kling 4.0 Image to Video API

POST/api/v1/run/kuaishou/kling-4.0/image-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
`image_url`required	string (URL)	Image used as the opening frame. JPG/PNG/WebP, URL or upload.	No
`end_image_url`	string (URL)	Optional closing frame — the model animates between the two.	No
`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/image-to-video`, {
  method: "POST",
  headers,
  body: JSON.stringify({
    "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
  }),
}).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/image-to-video", headers=headers, json={
    "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
}).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/image-to-video \
  -H "Authorization: Bearer $CHEAPERGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "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
}'

Response

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "kuaishou/kling-4.0",
  "endpoint": "kuaishou/kling-4.0/image-to-video",
  "mode": "image-to-video",
  "status": "queued",
  "input": {
    "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
  },
  "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/image-to-video",
  "mode": "image-to-video",
  "status": "succeeded",
  "input": {
    "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
  },
  "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 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"
}

Get the result

Generations are asynchronous. Poll until status is succeeded, failed or canceled — or pass webhook_url when you submit. Failed generations are refunded automatically.

curl https://cheapergen.com/api/v1/generations/gen_8c2QmX1nq0k4 \
  -H "Authorization: Bearer $CHEAPERGEN_API_KEY"

200 — succeeded

{
  "status": "succeeded",
  "output": {
    "video": {
      "url": "https://cdn.cheapergen.com/outputs/gen_8c2Q.mp4",
      "content_type": "video/mp4"
    }
  }
}

More: job lifecycle · webhooks · errors

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.