# Kling 4.0 (Text to Video)

Kling 4.0 text-to-video, 3-30s at 720p or 1080p. Always generates native audio.

- Model ID: `kling/kling-4.0-text-to-video`
- Provider: Kling (Kuaishou)
- Modality: text → video
- Type: Text to Video
- Status: stable
- Delivery: async
- Max resolution: 1080p
- Output format: mp4
- Aspect ratios: 21:9, 16:9, 9:16, 1:1

## Authentication

Send your API key in the `X-API-Key` header.

The same key reads the org balance at `GET https://api.dev.pika.art/billing/balance`, which is free to call and confirms the request can be paid for before you submit it.

## Endpoint

```
POST https://api.dev.pika.art/v1/media/kling/kling-4.0/text-to-video
```

## Reference uploads

To use a local file (image, audio, or video) as a model input, first request a presigned upload URL: `POST /v1/media/uploads` with the `X-API-Key` header and a JSON body `{ "content_type": "image/png", "size_bytes": 12345 }`, where `size_bytes` is the file's exact byte length. The response returns `upload_url` (temporary, valid for 5 minutes), `headers`, and `url` (the permanent Pika URL). PUT the file bytes to `upload_url` sending the returned `headers` verbatim — both `Content-Type` and `Content-Length` are signed, and storage returns a bare 403 if either is missing or differs. Then pass `url` into fields such as `image`, `image_url`, `end_image_url`, `image_urls`, `first_frame_image`, or `mask_image_url`.

## Generate

`POST /v1/media/kling/kling-4.0/text-to-video`

```bash
curl -X POST https://api.dev.pika.art/v1/media/kling/kling-4.0/text-to-video \
  -H "X-API-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "prompt": "SCENE: wide 16:9, long-lens compression, camera low on the road. An empty dusty-pink desert road running straight to a distant flat-topped mesa under a soft overcast sky, scrub brush and pale sand either side. A Mexican man in his thirties with a moustache, in a cream cowboy hat, cream cowboy boots and a costumey emerald sequinned western suit with silver yoke trim, pushes a supermarket trolley heaped with whole striped watermelons along the road edge on the left third, walking with purpose. A single tiny white pickup truck far behind on the road. Palette: dusty rose desert against emerald sequins and watermelon green.\nCAMERA: starts low and close at road level beside the trolley, then cranes up and pulls back high above the road in one continuous move, revealing the vast empty desert, the long road and the mesa, the man and his trolley becoming small. The high wide shot is framed to KEEP THE RUNAWAY WATERMELON IN FRAME the whole time.\nACTION / STORY: 0-3s he pushes the trolley forward, one wheel squeaking and wobbling, sequins glittering. 3-6s the trolley jolts over a crack and one watermelon tumbles off the top and rolls away ahead of him down the middle of the road; he stops and watches it go, deadpan. 6-10s he sighs and keeps pushing the trolley onward toward the mesa as the camera rises into the high wide shot. CRITICAL CONTINUITY: in the high wide shot the single runaway watermelon is clearly visible on the road - a distinct dark-green striped ball still rolling along the centre line well ahead of the man, kicking up a tiny puff of dust, a clear gap of road between it and the trolley, with the distant pickup truck further down the road beyond it. The watermelon never disappears from frame.\nAUDIO: a squeaky wobbling trolley wheel, the hollow thump of the watermelon hitting asphalt and rolling, sequins rustling, dry desert wind, a far-off engine. Sparse twangy western guitar. No speech.\nLOOK: a real 35mm film photograph in motion, never a 3D render. Soft, diffused, even, dimensional light; low-to-moderate contrast; colour true, soft but vibrant, never washed out; creamy highlight roll-off, a touch of warmth, light natural film grain, no HDR or sharpening. Skin with real photographic texture - pores, fine hairs, freckles. Anatomy correct: every person has exactly two arms and two hands with five fingers, no extra limbs. No visible text, logos or branding anywhere. SPEED IS CRITICAL: everything moves at normal real-time speed, like 24fps footage played back at 24fps - natural motion, NO slow motion.",
  "duration": 10,
  "resolution": "720p",
  "aspect_ratio": "16:9"
}'
```

### Request body

| Param | Type | Required | Default | Description |
| --- | --- | --- | --- | --- |
| `prompt` | string | yes | - | Text prompt describing the video. |
| `duration` | integer (3 – 30) | no | 5 | Video length in seconds. |
| `resolution` | enum | no | 720p | Output resolution. |
| `aspect_ratio` | enum | no | 16:9 | Output aspect ratio. |

#### Example body

```json
{
  "prompt": "SCENE: wide 16:9, long-lens compression, camera low on the road. An empty dusty-pink desert road running straight to a distant flat-topped mesa under a soft overcast sky, scrub brush and pale sand either side. A Mexican man in his thirties with a moustache, in a cream cowboy hat, cream cowboy boots and a costumey emerald sequinned western suit with silver yoke trim, pushes a supermarket trolley heaped with whole striped watermelons along the road edge on the left third, walking with purpose. A single tiny white pickup truck far behind on the road. Palette: dusty rose desert against emerald sequins and watermelon green.\nCAMERA: starts low and close at road level beside the trolley, then cranes up and pulls back high above the road in one continuous move, revealing the vast empty desert, the long road and the mesa, the man and his trolley becoming small. The high wide shot is framed to KEEP THE RUNAWAY WATERMELON IN FRAME the whole time.\nACTION / STORY: 0-3s he pushes the trolley forward, one wheel squeaking and wobbling, sequins glittering. 3-6s the trolley jolts over a crack and one watermelon tumbles off the top and rolls away ahead of him down the middle of the road; he stops and watches it go, deadpan. 6-10s he sighs and keeps pushing the trolley onward toward the mesa as the camera rises into the high wide shot. CRITICAL CONTINUITY: in the high wide shot the single runaway watermelon is clearly visible on the road - a distinct dark-green striped ball still rolling along the centre line well ahead of the man, kicking up a tiny puff of dust, a clear gap of road between it and the trolley, with the distant pickup truck further down the road beyond it. The watermelon never disappears from frame.\nAUDIO: a squeaky wobbling trolley wheel, the hollow thump of the watermelon hitting asphalt and rolling, sequins rustling, dry desert wind, a far-off engine. Sparse twangy western guitar. No speech.\nLOOK: a real 35mm film photograph in motion, never a 3D render. Soft, diffused, even, dimensional light; low-to-moderate contrast; colour true, soft but vibrant, never washed out; creamy highlight roll-off, a touch of warmth, light natural film grain, no HDR or sharpening. Skin with real photographic texture - pores, fine hairs, freckles. Anatomy correct: every person has exactly two arms and two hands with five fingers, no extra limbs. No visible text, logos or branding anywhere. SPEED IS CRITICAL: everything moves at normal real-time speed, like 24fps footage played back at 24fps - natural motion, NO slow motion.",
  "duration": 10,
  "resolution": "720p",
  "aspect_ratio": "16:9"
}
```

### Accepted values

| Param | Values | Default |
| --- | --- | --- |
| `resolution` | `720p`, `1080p` | `720p` |
| `aspect_ratio` | `21:9`, `16:9`, `9:16`, `1:1` | `16:9` |

Returns a job object, not the final output — normally with status `queued`. If you're at your concurrency limit, the job stays `queued` until a slot frees up, then starts on its own. Store the `id` and poll until a terminal state. A rejected submit (insufficient balance, rate limit, unpriceable input) still returns the job object, with status `failed` and `error` set. An `Idempotency-Key` replay returns the existing job in its current state — including `failed`, so retry a failure with a fresh key, never the same one.

### Response

**200 OK · queued**

```json
{
  "id": "media_8f3a2c91-5b7d-4e0a-9c26-31d4f2a8e6b0",
  "status": "queued"
}
```

## Poll status

`GET /v1/media/jobs/{request_id}`

```bash
curl https://api.dev.pika.art/v1/media/jobs/{request_id} \
  -H "X-API-Key: YOUR_API_KEY"
```

Poll the job by id until it reaches a terminal state: `completed` or `failed`.

### The job object

- `id` (string): Unique identifier for the job.
- `status` (enum): One of `queued`, `running`, `completed`, `failed`.
- `output` (object): Present once the job completes.
  - `media_type` (enum): `video`.
  - `output.video.url` (string): URL of the generated video.
- `error` (object): Present if the job failed. `error.code` is the stable machine-readable value to branch on — one of `invalid_input`, `content_moderation`, `provider_error`, `provider_timeout`, `provider_unavailable`, `rate_limited`, `insufficient_balance`, `membership_required`, `cycle_limit_exceeded`, `admission_suspended`, `timed_out`, `internal`. Unrecognized values normalize to `provider_error`. `error.message` is diagnostic text and varies.
- `usage` (object): Units the provider reported for the job, such as `video_output_tokens`, `image_output_tokens`, `input_tokens`, or `output_seconds`. Present once the job is terminal, carries only the units the job reports, and is `null` when nothing was reported. It may not reproduce the charge, because some pricing components are fixed by the request; the charge is authoritative.
- `billing` (object): What the job charged. Present once the job is terminal, `null` on the submit response and on webhooks. `billing.state` is one of `settled`, `pending`, `unavailable`. `settled` carries `charge_micro_usd`, the amount collected in micro-USD (the balance's unit), `0` included. `pending` means the charge is still settling: retry at 1s, 2s, then 5s. `unavailable` means the billing read failed on Pika's side: retry no sooner than 30s. Record spend only when `state` is `settled`, keyed by job id; a `billing` of `null` is not a charge.

### Response

**200 OK · running**

```json
{
  "id": "media_8f3a2c91-5b7d-4e0a-9c26-31d4f2a8e6b0",
  "status": "running"
}
```

**200 OK · completed**

```json
{
  "id": "media_8f3a2c91-5b7d-4e0a-9c26-31d4f2a8e6b0",
  "status": "completed",
  "output": {
    "media_type": "video",
    "video": {
      "url": "https://api.dev.pika.art/v1/files/video_8f3a2c91.mp4",
      "content_type": "video/mp4"
    }
  },
  "usage": {
    "video_output_tokens": 50638
  },
  "billing": {
    "state": "settled",
    "charge_micro_usd": 372189
  }
}
```

**200 OK · failed**

```json
{
  "id": "media_8f3a2c91-5b7d-4e0a-9c26-31d4f2a8e6b0",
  "status": "failed",
  "error": {
    "code": "provider_error",
    "message": "upstream generation failed"
  },
  "billing": {
    "state": "settled",
    "charge_micro_usd": 0
  }
}
```

A completed job carries its download URL in `output`. `GET /v1/media/jobs/{request_id}/content` returns that same URL as `{ "url": "..." }` for clients that only kept the id; it answers `409` until the job completes.

## Errors

Errors use conventional HTTP status codes and always return JSON, in one of two shapes. Request-level errors (auth, unknown path, schema validation, idempotency conflict) are `{"message": "..."}`. Submit rejections that occur after the job row is created (insufficient balance, rate limit, unpriceable input, dispatch unavailable) return the full failed job envelope — branch on `error.code`, and retry with a fresh `Idempotency-Key`, since a failed job replays on its key.

- 401 Unauthorized — The API key is missing or invalid. Body: `{"message":"Invalid API key"}`
- 403 Forbidden — An inactive key is rejected with a `{"message"}` body. A submit that the org balance or postpaid cycle limit cannot cover is rejected after the job row exists and returns the failed job envelope. `GET /billing/balance` separates the two: a `200` means the key is active, so the rejection was the balance or the cycle limit. Body: `{"id":"media_8f3a2c91-5b7d-4e0a-9c26-31d4f2a8e6b0","status":"failed","error":{"code":"insufficient_balance","message":"Insufficient org balance"}}`
- 404 Not Found — No job with that id exists in your org, or the media path names an unknown vendor/model/function. Body: `{"message":"media job not found"}`
- 409 Conflict — The result was requested before the job completed, or an Idempotency-Key header was reused with a different body. Body: `{"message":"media job is not ready"}`
- 422 Unprocessable Entity — The request body failed validation: an invalid enum value, a missing required field, a wrong type, or malformed JSON. The JSON message names the offending field. A schema-valid parameter combination that cannot be priced instead fails after job creation and returns the failed job envelope with error code `invalid_input`. Body: `{"message":"duration: Input should be less than or equal to 15"}`
- 429 Too Many Requests — You've hit your per-minute or per-day request limit, or your org's job queue is full. Returned as the failed job envelope. If there's a Retry-After header, wait that long, then retry with a fresh Idempotency-Key. Body: `{"id":"media_8f3a2c91-5b7d-4e0a-9c26-31d4f2a8e6b0","status":"failed","error":{"code":"rate_limited","message":"rate limit exceeded: rpm"}}`
- 503 Service Unavailable — The model rail or a backend dependency is temporarily unavailable. Returned as the failed job envelope; retry with backoff and a fresh Idempotency-Key. Body: `{"id":"media_8f3a2c91-5b7d-4e0a-9c26-31d4f2a8e6b0","status":"failed","error":{"code":"provider_unavailable","message":"media dispatch unavailable"}}`

## Pricing

- 720p: $0.157 per second
- 1080p: $0.235 per second

Only successful generations are charged.

Check the balance against this price before submitting: `GET https://api.dev.pika.art/billing/balance` returns `balance_micro_usd`, which is US dollars multiplied by 1,000,000, and `postpaid` when the org bills by invoice instead. For an active postpaid org, compare the price against `postpaid.cycle.remaining_micro_usd` rather than the prepaid balance. Report a shortfall to the user rather than submitting a request the balance cannot cover.

---

Model page: https://dev.pika.art/models/kling/kling-4.0/text-to-video
API index: https://dev.pika.art/llms.txt