# Kling Kling v2.1 Pro — Image To Video

> Access the Kling 2.1 Pro API for elite motion-focused AI video. Get pro-grade generation with precise physics and cost-effective per-second rates at GPTProto.com.

## Overview

- **Endpoint**: `POST https://gptproto.com/api/v3/kling/kling-v2.1-pro/image-to-video`
- **Result URL**: `GET https://gptproto.com/api/v3/predictions/{result_id}/result` — the submit response also returns the authoritative URL in `data.urls.get`
- **Model ID**: `kling-v2.1-pro`
- **Vendor**: Kling
- **Scene**: `image-to-video`
- **Category**: image-to-video
- **Modalities**: input image → output video
- **Playground**: https://gptproto.com/model/kling/kling-v2.1-pro
- **API documentation**: https://docs.gptproto.com/docs/allapi/Kling/kling-v2.1-pro/gptproto-format/image-to-video
- **Other scenes of this model**: `start-end-frame` — same auth, different endpoint path and input schema

## Authentication

Every request needs a GPTProto API key in the `Authorization` header. Create one at https://gptproto.com/dashboard/api-key, then export it:

```bash
export GPTPROTO_API_KEY="your-api-key"
```

Header: `Authorization: Bearer $GPTPROTO_API_KEY` (plus `Content-Type: application/json` on POST).

## Pricing

Platform price by tier (USD, already includes the GPTProto discount):

- **5** — $0.392 per run
- **10** — $0.784 per run

Price range: $0.392 – $0.784 per generation.

Prices may change. The model page always shows the live price: https://gptproto.com/model/kling/kling-v2.1-pro

## API Information

The API is asynchronous: POST the endpoint to create a prediction, then poll its result URL until `status` is `completed` or `failed`.

### Input Schema

The endpoint accepts the following JSON body parameters:

- **`prompt`** (`string`, _required_):
  The positive prompt for the generation.

- **`negative_prompt`** (`string`, _optional_):
  The negative prompt for the generation.

- **`image`** (`string`, _required_):
  First frame of the video; Supported image formats include:.jpg/.jpeg/.png; The image file size cannot exceed 10MB, and the image resolution should not be less than 300*300px.

- **`guidance_scale`** (`range`, _optional_):
  The guidance scale to use for the generation.
  - Default: `0.5`
  - Range: 0–1

- **`duration`** (`enum`, _optional_):
  The duration of the generated media in seconds.
  - Default: `5`
  - Options: 5, 10

**Required Parameters Example**:

```json
{
  "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle",
  "image": "https://tos.gptproto.com/resource/cat.png"
}
```

**Full Example**:

```json
{
  "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle",
  "negative_prompt": "",
  "image": "https://tos.gptproto.com/resource/cat.png",
  "guidance_scale": 0.5,
  "duration": 5
}
```

### Output Schema

Both submit and poll return the same envelope:

- **`data.id`** (`string`): Prediction id. Use it as `result_id` when polling for the result.
- **`data.status`** (`string`): One of `created`, `running`, `completed`, `failed`. See Status Values below.
- **`data.outputs`** (`array of string`): Generated files. Empty until `status` is `completed`; then it holds the output URLs (or base64 strings when the model exposes a base64 option).
- **`data.urls.get`** (`string`): Authoritative result URL for this prediction. Prefer it over building the poll URL yourself.
- **`data.error`** (`string | null`): Failure reason when `status` is `failed`, otherwise `null`.
- **`data.executionTime`** (`integer`): Total processing time in milliseconds.
- **`data.timings.inference`** (`integer`): Model inference time in milliseconds.
- **`data.hasNsfwContents`** (`array of boolean`): Per-output moderation flags.
- **`message`** (`string`): `success` on a normal response, otherwise the error message.
- **`code`** (`integer`): Business status code. `200` means the request was accepted.

**Example Response — submit (task accepted)**:

```json
{
    "data": {
        "id": "pred_example_01",
        "model": "kling-v2.1-pro",
        "outputs": [],
        "urls": {
            "get": "https://gptproto.com/api/v3/predictions/pred_example_01/result"
        },
        "hasNsfwContents": [],
        "status": "created",
        "createdAt": "2026-01-01T12:00:00Z",
        "executionTime": 0,
        "timings": {
            "inference": 0
        }
    },
    "message": "success",
    "code": 200
}
```

**Example Response — poll (completed)**:

```json
{
    "data": {
        "id": "pred_example_01",
        "model": "kling-v2.1-pro",
        "outputs": [
            "https://oss-us.gptproto.com/example/output.mp4"
        ],
        "urls": {
            "get": "https://gptproto.com/api/v3/predictions/pred_example_01/result"
        },
        "status": "completed",
        "error": null,
        "executionTime": 12345,
        "timings": {
            "inference": 12000
        },
        "has_nsfw_contents": [],
        "created_at": "2026-01-01T12:00:00Z"
    },
    "message": "success",
    "code": 200
}
```

### Status Values

- `created` — Task accepted. Use `data.id` as `result_id` for polling.
- `running` — Generation is in progress. Keep polling.
- `completed` — Finished successfully. Generated files are in `data.outputs`.
- `failed` — Generation failed. Read `data.error` for the reason.

## Usage Examples

### 1. Submit a request

```bash
curl --request POST "https://gptproto.com/api/v3/kling/kling-v2.1-pro/image-to-video" \
    --header "Authorization: Bearer $GPTPROTO_API_KEY" \
    --header "Content-Type: application/json" \
    --data '{
        "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle",
        "negative_prompt": "",
        "image": "https://tos.gptproto.com/resource/cat.png",
        "guidance_scale": 0.5,
        "duration": 5
    }'
```

```python
import os
import requests

url = "https://gptproto.com/api/v3/kling/kling-v2.1-pro/image-to-video"
headers = {
    "Authorization": f"Bearer {os.environ['GPTPROTO_API_KEY']}",
    "Content-Type": "application/json"
}
payload = {
    "prompt": "A tiny origami fox sailing a teacup across a moonlit puddle",
    "negative_prompt": "",
    "image": "https://tos.gptproto.com/resource/cat.png",
    "guidance_scale": 0.5,
    "duration": 5
}

response = requests.request("POST", url, headers=headers, json=payload)
print(response.json())
```

```typescript
const response = await fetch("https://gptproto.com/api/v3/kling/kling-v2.1-pro/image-to-video", {
    method: "POST",
    headers: {
        "Authorization": `Bearer ${process.env.GPTPROTO_API_KEY}`,
        "Content-Type": "application/json",
    },
    body: JSON.stringify({
        prompt: "A tiny origami fox sailing a teacup across a moonlit puddle",
        negative_prompt: "",
        image: "https://tos.gptproto.com/resource/cat.png",
        guidance_scale: 0.5,
        duration: 5,
    }),
});

const data = await response.json();
console.log(data);
```

### 2. Poll until the task finishes

Replace `YOUR_RESULT_ID` with `data.id` from the submit response (or call `data.urls.get` directly), and keep polling every 1–3 seconds while `status` is `created` or `running`.

```bash
result_id="YOUR_RESULT_ID"

curl --request GET "https://gptproto.com/api/v3/predictions/$result_id/result" \
    --header "Authorization: Bearer $GPTPROTO_API_KEY"
```

```python
import os
import requests

result_id = "YOUR_RESULT_ID"
url = f"https://gptproto.com/api/v3/predictions/{result_id}/result"
headers = {
    "Authorization": f"Bearer {os.environ['GPTPROTO_API_KEY']}"
}
response = requests.request("GET", url, headers=headers)
print(response.json())
```

```typescript
const result_id = "YOUR_RESULT_ID";
const response = await fetch(`https://gptproto.com/api/v3/predictions/${result_id}/result`, {
    method: "GET",
    headers: {
        "Authorization": `Bearer ${process.env.GPTPROTO_API_KEY}`,
    },
});

const data = await response.json();
console.log(data);
```

## Example Prompts

- In soft golden afternoon light, a young girl stands amidst a forest of autumn maples, a vivid crimson leaf resting in her fingertips. She smiles subtly, her hair drifting in the breeze, as warm sunlight illuminates the leaf’s delicate veins.
- From a handheld camera viewpoint, a cat sits in the pilot’s seat inside the cockpit, its ears twitching as it turns its head left and right to watch the horizon. Through the windows, the aircraft glides steadily above a rolling sea of bright white clouds, sunlight spilling across…
- A busy street in Tokyo at night after rain. People are walking by, blurred reflections of neon signs and city lights on the wet pavement. Tilt-shift effect, cinematic, detailed, street photography, moody lighting, 4K, time-lapse feel.

## HTTP Status Codes

- `400` — malformed body, a parameter or value this model does not accept, or input blocked by the provider's content moderation
- `401` — missing or invalid API key
- `403` — insufficient credits
- `413` — request body too large
- `429` — rate limited; retry with backoff
- `500` — An internal server error occurred
- `502` — An internal server error occurred
- `504` — Gateway timeout — upstream service did not respond in time; retry later

## Additional Resources

- [Model playground](https://gptproto.com/model/kling/kling-v2.1-pro)
- [API documentation](https://docs.gptproto.com/docs/allapi/Kling/kling-v2.1-pro/gptproto-format/image-to-video)
- [All models](https://gptproto.com/model)
- [API keys](https://gptproto.com/dashboard/api-key)
- [Platform overview for LLMs](https://gptproto.com/llms-full.txt)
- Any other model: `https://gptproto.com/model/{vendor}/{model}/{scene}/llms.txt`