# Kling 4.0 API Documentation

> LLM-optimized documentation for Kling 4.0. Copy into your AI assistant for integration help.

## Overview

**Model ID:** `kling-4-0`
**Type:** Video Generation
**Credit Cost:** 25 credits per video

Kling Video 4.0. Up to 30 seconds at 1080p with native audio and dialogue: text, start/end frames, reference images and videos, or edit an existing clip.

## Endpoint

```
POST https://pixeldojo.ai/api/v1/models/kling-4-0/run
```

## Authentication

All requests require an API key in the Authorization header:

```
Authorization: Bearer YOUR_API_KEY
```

Get your API key: https://pixeldojo.ai/api-platform/api-keys

## Input Parameters

| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| `prompt` | string | Yes | - | What happens in the clip. Timed beats, camera moves and quoted dialogue all work. Refer to inputs as <<<image_1>>> (frames first, then reference images) and <<<video_1>>> (source video first, then reference videos). |
| `image` | url | No | - | Optional first frame. The image sets the aspect ratio. |
| `last_frame_image` | url | No | - | Optional last frame. Requires image. |
| `reference_images` | array | No | - | Up to 10 images (frames included) for cast, products, locations or a storyboard. |
| `video` | url | No | - | A clip to edit with the prompt (swap a product, add or remove a subject, restyle). Set duration to the clip length; billed at the video-input rate. |
| `reference_videos` | array | No | - | Up to 5 clips (30 s total) whose motion, camera path or structure to carry over. Billed at the video-input rate. |
| `resolution` | enum | No | 1080p | Output resolution (Options: 720p, 1080p) |
| `aspect_ratio` | enum | No | 16:9 | Text-to-video only; inputs set their own shape. (Options: 16:9, 9:16, 1:1, 21:9) |
| `duration` | integer | No | 5 | Clip length in seconds (3-30). With video, the source clip length. (min: 3, max: 30) |

## Supported Aspect Ratios

- `16:9`
- `9:16`
- `1:1`
- `21:9`

## Capabilities

- Text to Video
- Image to Video
- Audio Generation

## Quick Start

### 1. Submit a Job

```bash
curl -X POST "https://pixeldojo.ai/api/v1/models/kling-4-0/run" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "0-4s: slow push in on a barista in a rainy cafe. 4-10s: she looks up and says \"Last order of the night.\" Audio: rain on glass, espresso hiss.",
    "duration": 10,
    "resolution": "1080p"
  }'
```

**Response:**
```json
{
  "jobId": "job_abc123...",
  "status": "pending",
  "statusUrl": "https://pixeldojo.ai/api/v1/jobs/job_abc123",
  "creditCost": 25,
  "creditsRemaining": 95
}
```

### 2. Poll for Results

```bash
curl "https://pixeldojo.ai/api/v1/jobs/job_abc123" \
  -H "Authorization: Bearer YOUR_API_KEY"
```

**Completed Response:**
```json
{
  "jobId": "job_abc123...",
  "status": "completed",
  "output": {
    "video": "https://temp.pixeldojo.ai/..."
  },
  "creditCost": 25
}
```

## Python Example

```python
import requests
import time

API_KEY = "YOUR_API_KEY"

# Submit job
response = requests.post(
    "https://pixeldojo.ai/api/v1/models/kling-4-0/run",
    headers={
        "Authorization": f"Bearer {API_KEY}",
        "Content-Type": "application/json"
    },
    json={
        "prompt": "0-4s: slow push in on a barista in a rainy cafe. 4-10s: she looks up and says \"Last order of the night.\" Audio: rain on glass, espresso hiss.",
        "duration": 10,
        "resolution": "1080p"
    }
)

job = response.json()
job_id = job["jobId"]

# Poll for completion
while True:
    status_response = requests.get(
        f"https://pixeldojo.ai/api/v1/jobs/{'{job_id}'}",
        headers={"Authorization": f"Bearer {API_KEY}"}
    )
    status = status_response.json()
    
    if status["status"] == "completed":
        print("Output:", status["output"])
        break
    elif status["status"] == "failed":
        print("Error:", status.get("error"))
        break
    
    time.sleep(2)
```

## JavaScript Example

```javascript
const API_KEY = 'YOUR_API_KEY';

// Submit job
const submitResponse = await fetch('https://pixeldojo.ai/api/v1/models/kling-4-0/run', {
  method: 'POST',
  headers: {
    'Authorization': `Bearer ${API_KEY}`,
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    "prompt": "0-4s: slow push in on a barista in a rainy cafe. 4-10s: she looks up and says \"Last order of the night.\" Audio: rain on glass, espresso hiss.",
    "duration": 10,
    "resolution": "1080p"
  })
});

const job = await submitResponse.json();

// Poll for completion
const pollForResult = async (jobId) => {
  while (true) {
    const statusResponse = await fetch(`https://pixeldojo.ai/api/v1/jobs/${jobId}`, {
      headers: { 'Authorization': `Bearer ${API_KEY}` }
    });
    const status = await statusResponse.json();
    
    if (status.status === 'completed') return status.output;
    if (status.status === 'failed') throw new Error(status.error);
    
    await new Promise(r => setTimeout(r, 2000));
  }
};

const output = await pollForResult(job.jobId);
console.log('Output:', output);
```

## Use Saved Characters (@Name)

Write `@Name` in the prompt to use a character, product, outfit, location, prop or style saved in the account's Character Studio, for example `"@Mara on a beach at sunset"`. Its photos are added to `reference_images` automatically, after any images you send yourself, so your own image numbering is unchanged. List saved names with `GET /api/v1/characters` and save new ones with `POST /api/v1/characters`. An `@word` that names nothing saved stays plain text.

## Error Codes

| Code | Status | Description |
|------|--------|-------------|
| `unauthorized` | 401 | Invalid or missing API key |
| `insufficient_credits` | 402 | Not enough credits |
| `invalid_request` | 400 | Invalid parameters |
| `model_not_found` | 404 | Model ID not found |
| `internal_error` | 500 | Server error |

## Links

- **Full Documentation:** https://pixeldojo.ai/api-platform/kling-4-0
- **API Keys:** https://pixeldojo.ai/api-platform/api-keys
- **Buy Credits:** https://pixeldojo.ai/api-platform/buy-credits
- **All Models:** https://pixeldojo.ai/api/v1/models
- **OpenAPI Spec:** https://pixeldojo.ai/api/openapi