# Kling 4.0 API (Kuaishou)

> Kuaishou Kling 4.0 generates 3–30 second videos at 720p or 1080p with stereo sound, from text, a first and last frame, or reference images and videos.

Page: https://cheapergen.com/models/kuaishou/kling-4.0 · API reference: https://cheapergen.com/models/kuaishou/kling-4.0/api · Live status and uptime: https://cheapergen.com/models/kuaishou/kling-4.0/status

Our prices updated 2026-11-15: CheaperGen prices are live, and this file is regenerated every 5 minutes. Third-party prices keep the dates they were checked.

## Pricing
Official list price source: 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.

| Tier | Official | CheaperGen | Save |
|---|---|---|---|
| 720p | $0.1570/s | $0.1486/s | 5% |
| 1080p | $0.2350/s | $0.2226/s | 5% |

Monthly plans (Pro, Max) lower the price on most models while they're active: https://cheapergen.com/pricing#plans. Volume pricing for larger teams: https://cheapergen.com/enterprise#contact.

## Cheapest Kling 4.0 API: 3 providers compared (third-party prices checked 2026-11-08)
The cheapest Kling 4.0 API we found is CheaperGen, at $0.1486/s (720p). That's 5% below Kuaishou's official $0.157/s, and below the 2 other platforms compared here.

| Provider | 720p | 1080p | Price date |
|---|---|---|---|
| CheaperGen (live price) | $0.1486/s | $0.2226/s | live, 2026-11-15 |
| Kuaishou (official) | $0.157/s | $0.235/s | verified October 18, 2026 |
| fal | $0.157/s | $0.235/s | 2026-11-08 |
| Replicate | $0.157/s | $0.235/s | 2026-11-08 |

CheaperGen prices are live. Other platforms: public list prices, checked on the dates shown; not every platform is listed. Sources: fal https://fal.ai/models/kling/v4/text-to-video, Replicate https://replicate.com/kwaivgi/kling-v4.0.
Full comparison: https://cheapergen.com/models/kuaishou/kling-4.0/cheapest

## Specs
- Resolutions: 720p · 1080p
- Duration: 3–30 s
- Aspect ratios: 16:9 · 9:16 · 1:1 · 21:9
- Audio: Always on (included)
- Inputs: Text, first/last frame, or up to 10 reference images and 5 reference videos

## Endpoints

### Text to Video — `POST https://cheapergen.com/api/v1/run/kuaishou/kling-4.0/text-to-video`

| Param | Type | Required | Description |
|---|---|---|---|
| prompt | string | yes | Describe the shot: subject, action, camera movement, lighting and style. |
| aspect_ratio | string (enum) (16:9, 9:16, 1:1, 21:9) | no | Output frame shape. |
| resolution | string (enum) (720p, 1080p) | no | Output resolution. Higher resolutions cost more per second. |
| duration | integer (3–30) | no | Length of the generated clip in seconds (3–30s). You pay per second. |

```bash
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
}'
```

### Image to Video — `POST https://cheapergen.com/api/v1/run/kuaishou/kling-4.0/image-to-video`

| Param | Type | Required | Description |
|---|---|---|---|
| prompt | string | yes | Describe the shot: subject, action, camera movement, lighting and style. |
| image_url | string (URL) | yes | Image used as the opening frame. JPG/PNG/WebP, URL or upload. |
| end_image_url | string (URL) | no | Optional closing frame — the model animates between the two. |
| resolution | string (enum) (720p, 1080p) | no | Output resolution. Higher resolutions cost more per second. |
| duration | integer (3–30) | no | Length of the generated clip in seconds (3–30s). You pay per second. |

```bash
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
}'
```

### Reference to Video — `POST https://cheapergen.com/api/v1/run/kuaishou/kling-4.0/reference-to-video`

| Param | Type | Required | Description |
|---|---|---|---|
| prompt | string | yes | Describe the shot: subject, action, camera movement, lighting and style. |
| reference_image_urls | string[] (URLs) | no | Up to 10 images for characters, products, style or scene. Refer to them in the prompt as @Image1, @Image2… |
| reference_video_urls | string[] (video URLs) | no | 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 | string (enum) (16:9, 9:16, 1:1, 21:9) | no | Output frame shape. |
| resolution | string (enum) (720p, 1080p) | no | Output resolution. Higher resolutions cost more per second. |
| duration | integer (3–30) | no | Length of the generated clip in seconds (3–30s). You pay per second. |

```bash
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
}'
```

## Getting the result
Jobs are async. Poll `GET https://cheapergen.com/api/v1/generations/{id}` until status is succeeded/failed/canceled, or pass `webhook_url`. Failed generations are refunded automatically.
When status is `succeeded`, the video is at `output.video.url` (with `output.video.content_type`).
Output URLs expire with the account's retention (1 day after the job finishes by default): download or re-host them.

## FAQ
**How is Kling 4.0 priced?**
Per second of output video at 720p or 1080p. 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. Failed generations are never charged.

**Is this the official Kling 4.0 model?**
Yes. Requests run on Kuaishou's Kling 4.0 — the same model and output quality as the Kling developer API, at a lower price.

**How long can a video be?**
Any whole number of seconds from 3 to 30, in one generation.

**How do references work?**
In Reference to Video, attach up to 10 images and up to 5 videos and mention them in the prompt as @Image1, @Image2… and @Video1, @Video2… — for example "@Image1 walks along the beach, following the camera move of @Video1".

**Can I use the output commercially?**
Yes, subject to Kuaishou's Kling usage policy and our Terms of Service.

Kling 4.0 is developed by Kuaishou. CheaperGen provides API access and does not own the model.