# Wan-2.1 First-Last-Frame-to-Video API

> Generador de video Wan 2.1 que anima la transición entre una imagen inicial y una final

Crea un clip que va de `start_image_url` a `end_image_url`, guiado por un `prompt`. La resolución es 480p o 720p y la relación de aspecto auto, 16:9, 9:16 o 1:1. `num_frames` es 81-100 y `frames_per_second` 5-24. Admite `negative_prompt`, `seed`, controles de guía y pasos, y pesos LoRA mediante `loras`.

- Model id: `wan-flf2v`
- Made by: Alibaba
- Category: Image to Video
- Output: video
- Price: from $0.20 / video (cheapest run $0.20 (200 API credits))
- Run: `POST https://api.doitong.com/v1/run/wan-flf2v`
- Quote: `POST https://api.doitong.com/v1/quote/wan-flf2v`
- Docs page: https://doitong.com/es/developers/models/wan-flf2v

## Pricing

Price: **from $0.20 / video** (the lowest tier; the quote prices your exact input). Billed once per generated video.

Price rules (the first rule that matches the input wins; a parameter you leave out counts as its default):

- When `num_frames` > 81 and `resolution` = 720p: $0.50 (500 API credits) / video
- When `resolution` = 720p: $0.40 (400 API credits) / video
- When `num_frames` > 81: $0.25 (250 API credits) / video

The full example input below costs $0.40 = 400 API credits (1 video × 400 API credits).

Prices are the upstream price in USD, paid from the API balance in API credits (1000 API credits = 1 USD). `POST https://api.doitong.com/v1/quote/wan-flf2v` with the same JSON body returns the exact price for that input; the quote is exactly what a run charges. Invalid input is never charged and failed or canceled requests are refunded automatically.

## Input parameters

Send either the canonical name or the native field name (not both). Canonical names are the same across models.

| Parameter | Canonical name | Type | Required | Default | Allowed values / range | Description |
|---|---|---|---|---|---|---|
| `prompt` |  | string | yes |  |  | Instrucciones de texto que orientan la generación de video. |
| `negative_prompt` |  | string | no | `bright colors, overexposed, static, blurred details, subtitles, style, artwork, painting, picture, still, overall gray, worst quality, low quality, JPEG compression residue, ugly, incomplete, extra fingers, poorly drawn hands, poorly drawn faces, deformed, disfigured, malformed limbs, fused fingers, still picture, cluttered background, three legs, many people in the background, walking backwards` |  | Prompt negativo aplicado al generar un video. |
| `start_image_url` | `image` | string (image URL) | yes |  |  | Proporciona la imagen inicial mediante URL; para igualar la relación de aspecto seleccionada, se cambia el tamaño y se recorta alrededor del centro cuando la relación de la imagen difiere. |
| `end_image_url` | `end_image` | string (image URL) | yes |  |  | Proporciona la imagen final mediante URL; para igualar la relación de aspecto seleccionada, se cambia el tamaño y se recorta alrededor del centro cuando la relación de la imagen difiere. |
| `num_frames` |  | integer \| null | no | `81` | 81 – 100 | Cantidad de fotogramas para la generación, de 81 a 100 inclusive. |
| `frames_per_second` |  | integer \| null | no | `16` | 5 – 24 | Frecuencia de fotogramas del video generado, en fotogramas por segundo, de 5 a 24. |
| `seed` |  | integer \| null | no |  |  | Semilla que hace reproducible la generación. Establecerla en None selecciona una semilla aleatoriamente. |
| `resolution` |  | enum (string) | no | `720p` | `480p`, `720p` | Resolución del video de salida, ya sea 480p o 720p. |
| `num_inference_steps` |  | integer | no | `30` | 2 – 40 | Cantidad de pasos de muestreo, que intercambia un mayor tiempo de procesamiento por una mejor calidad a medida que aumenta la cantidad. |
| `guide_scale` |  | number | no | `5` | 1 – 10 | Intensidad de guía sin clasificador, que intercambia una posible pérdida de calidad por una coincidencia más cercana con el prompt a medida que aumenta la escala. |
| `shift` |  | number | no | `5` | 1 – 10 | Configuración de desplazamiento aplicada al generar video. |
| `enable_safety_checker` |  | boolean | no | `false` |  | Interruptor de comprobación de seguridad cuyo estado desactivado requiere autorización de la cuenta. Sin esa autorización, todas las solicitudes se comprueban independientemente de la configuración; true activa el comprobador. |
| `enable_prompt_expansion` |  | boolean | no | `false` |  | Controla si la expansión del prompt está habilitada. |
| `acceleration` |  | enum (string) | no | `regular` | `none`, `regular` | Configuración de aceleración, con 'regular' como opción recomendada. Aumentar la aceleración sacrifica calidad para reducir el tiempo de generación. |
| `aspect_ratio` |  | enum (string) | no | `auto` | `auto`, `16:9`, `9:16`, `1:1` | Proporciones del video generado, seleccionadas automáticamente a partir de la imagen de entrada cuando se establecen en 'auto'. |
| `loras` |  | array of object {path, weight_name, scale} | no | `[]` |  | Pesos de LoRA aplicados durante la inferencia. |
| `loras[].path` |  | string | yes |  |  | Ubicación de los pesos de LoRA, especificada como URL o ruta. |
| `loras[].weight_name` |  | string \| null | no |  |  | Nombre del peso de LoRA, obligatorio solo cuando un repositorio de Hugging Face contiene más de 1 archivo safetensors. Este nombre solo se usa cuando `path` identifica dicho repositorio. |
| `loras[].scale` |  | number | no | `1` | 0 – 4 | Multiplicador aplicado al peso de LoRA antes de combinarlo con el modelo base. |

File parameters (`image`, `end_image`) take a public `https://` URL, a `data:` URI up to 10 MB, or the `file_url` of an upload from `POST /files`.

## Example input

Required parameters only:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
  "image": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
  "end_image": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
}
```

A fuller example:

```json
{
  "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
  "start_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
  "end_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
}
```

## Run it

Set `DOITONG_API_KEY` to a key from https://doitong.com/developers/dashboard#keys. `?wait=20` returns the finished request in the same call when it is ready within 20 seconds; otherwise poll `GET /requests/{id}` (it also accepts `?wait=`), or pass `webhook_url`.

### curl

```bash
# Run the model; wait up to 20 s for the finished result in the same call
curl -X POST "https://api.doitong.com/v1/run/wan-flf2v?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
    "start_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
    "end_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
  }'

# Still "queued" or "running"? Poll with the id from the response:
curl "https://api.doitong.com/v1/requests/REQUEST_ID?wait=20" \
  -H "Authorization: Bearer $DOITONG_API_KEY"
```

### JavaScript

```javascript
const API = "https://api.doitong.com/v1";
const headers = {
  "Authorization": "Bearer " + process.env.DOITONG_API_KEY,
  "Content-Type": "application/json",
};

// Run the model; wait up to 20 s for the finished result in the same call
let res = await fetch(API + "/run/wan-flf2v?wait=20", {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
    "start_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
    "end_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
  }),
});
let request = await res.json();
if (!res.ok) throw new Error(request.error.code + ": " + request.error.message);

// Not finished yet: long-poll until it is
while (request.status === "queued" || request.status === "running") {
  res = await fetch(API + "/requests/" + request.id + "?wait=20", { headers });
  request = await res.json();
}
if (request.status !== "succeeded") throw new Error(JSON.stringify(request.error));
console.log(request.outputs.map((o) => o.url), request.cost.credits + " API credits ($" + request.cost.usd + ")");
```

### Python

```python
import os
import requests

API = "https://api.doitong.com/v1"
headers = {"Authorization": "Bearer " + os.environ["DOITONG_API_KEY"]}

payload = {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
    "start_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
    "end_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
}

# Run the model; wait up to 20 s for the finished result in the same call
r = requests.post(API + "/run/wan-flf2v", params={"wait": 20}, json=payload, headers=headers)
request = r.json()
if not r.ok:
    raise RuntimeError(request["error"]["code"] + ": " + request["error"]["message"])

# Not finished yet: long-poll until it is
while request["status"] in ("queued", "running"):
    request = requests.get(API + "/requests/" + request["id"], params={"wait": 20}, headers=headers).json()
if request["status"] != "succeeded":
    raise RuntimeError(request["error"])
print([o["url"] for o in request["outputs"]], request["cost"]["credits"], "API credits", "$" + request["cost"]["usd"])
```

### MCP

The MCP server at `https://api.doitong.com/v1/mcp` exposes the tools `search_models`, `get_model`, `quote`, `run`, `get_request`, `cancel_request`, `list_requests`, `create_upload` and `get_account`. A `run` call for this model:

```json
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "run",
    "arguments": {
      "model_id": "wan-flf2v",
      "input": {
        "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
        "start_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
        "end_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
      },
      "wait_seconds": 20
    }
  }
}
```

## Response

Every call returns a request object. `status` is one of `queued`, `running`, `succeeded`, `failed`, `canceled`. `outputs` lists the generated files with URLs on our storage (kept forever, or 7 days with `?storage=temporary`; `storage` says which); `output` is the model's own result object with the same URLs.

```json
{
  "id": "req_8k2m4q7x1z9c3v5b6n0p2r4t",
  "object": "request",
  "model": "wan-flf2v",
  "status": "succeeded",
  "created_at": "2026-10-20T12:00:00Z",
  "started_at": "2026-10-20T12:00:02Z",
  "completed_at": "2026-10-20T12:00:09Z",
  "queue_position": null,
  "cost": {
    "credits": 400,
    "usd": "0.40",
    "charged": 400,
    "refunded": 0
  },
  "input": {
    "prompt": "A red fox trots through fresh snow at sunrise, soft golden light, shallow depth of field",
    "start_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg",
    "end_image_url": "https://content.doitong.com/images/showcase/v3/gen_fox_cartoon.jpg"
  },
  "output": {
    "video": {
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp4",
      "content_type": "video/mp4",
      "file_name": "0-output.mp4",
      "file_size": 1843200
    },
    "seed": 42
  },
  "outputs": [
    {
      "type": "video",
      "url": "https://content.doitong.com/dev-api/2026/10/20/req_8k2m4q7x1z9c3v5b6n0p2r4t/0-output.mp4",
      "content_type": "video/mp4",
      "file_size": 1843200,
      "width": 1280,
      "height": 720,
      "duration": 5,
      "stored": true
    }
  ],
  "error": null,
  "metrics": {
    "inference_seconds": 6.8
  },
  "urls": {
    "self": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t",
    "cancel": "https://api.doitong.com/v1/requests/req_8k2m4q7x1z9c3v5b6n0p2r4t/cancel"
  }
}
```

### Output fields (`output`)

| Field | Type | Description |
|---|---|---|
| `video` | object {url, content_type, file_name, file_size} | Archivo de video producido por la generación. |
| `seed` | integer | Valor de semilla aplicado durante la generación. |

## Related models

- [Wan-2.1 Pro Text-to-Video](https://doitong.com/developers/models/wan-pro/text-to-video.md) (`wan-pro/text-to-video`): $0.80 / run
- [Wan-2.1 Text-to-Video](https://doitong.com/developers/models/wan-t2v.md) (`wan-t2v`): from $0.20 / video
- [Wan Effects](https://doitong.com/developers/models/wan-effects.md) (`wan-effects`): $0.35 / video
- [Wan-2.1 Image-to-Video](https://doitong.com/developers/models/wan-i2v.md) (`wan-i2v`): from $0.20 / video
- [Wan-2.1 Pro Image-to-Video](https://doitong.com/developers/models/wan-pro/image-to-video.md) (`wan-pro/image-to-video`): $0.80 / video
- [Wan 3.0 Image to Video](https://doitong.com/developers/models/alibaba/wan-3.0/image-to-video.md) (`alibaba/wan-3.0/image-to-video`): from $0.05 / second
- [FLUX 3 Max Image to Video](https://doitong.com/developers/models/blackforestlabs/flux-3-max/image-to-video.md) (`blackforestlabs/flux-3-max/image-to-video`): from $0.0425 / second of output video
- [Grok Imagine Video 1.5 Image to Video](https://doitong.com/developers/models/xai/grok-imagine-video/v1.5/image-to-video.md) (`xai/grok-imagine-video/v1.5/image-to-video`): from $0.082 / second

## Links

- HTML page: https://doitong.com/developers/models/wan-flf2v
- All models and guides for AI agents: https://doitong.com/developers/llms.txt
- OpenAPI 3.1 with this model's typed request body: https://doitong.com/developers/openapi.json?model=wan-flf2v
- Errors: https://doitong.com/developers/docs/errors
- Model details as JSON: https://api.doitong.com/v1/models/wan-flf2v