# Veo 3.1 Fast API

> Lower-latency Veo for rapid iteration and previews.

- **Provider**: Google
- **Model id**: `veo-3-1-fast`
- **Modality**: video
- **Price**: 76.05–228.15 credits

## Overview

Veo 3.1 Fast is called in two steps: create a generation task, then poll the task until the result is ready.

## Authentication

All requests require a Bearer Token in the request header:

```
Authorization: Bearer YOUR_API_KEY
```

## Create Task

`POST https://you.bot/api/v1/generate`

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| modelId | string | Yes | Model id: `veo-3-1-fast` |
| input | object | Yes | Input parameters object (see below) |
| callbackUrl | string | No | https URL to receive a signed webhook on completion |

### input object parameters

| Parameter | Type | Required | Description |
|-----------|------|----------|-------------|
| prompt | string | Yes | Text value (default: A paper boat sails down a rain-swollen gutter after a storm, city lights reflecting in the stream. Audio: gentle rain, distant traffic.) |
| imageUrls | string[] | No | Image URL |
| aspectRatio | string | Yes | Options: Auto | 16:9 | 9:16 (default: Auto) |
| resolution | string | Yes | Options: 720p | 1080p | 4k (default: 720p) |
| duration | string | Yes | The duration of the generated video, in seconds. (options: 4s | 6s | 8s) (default: 8s) |

### Request example

```json
{
  "modelId": "veo-3-1-fast",
  "input": {
    "prompt": "A cinematic aerial shot of a coastal town at golden hour, gentle waves rolling onto the shore, warm light, slow camera push-in.",
    "imageUrls": [
      "https://example.com/input.jpg"
    ],
    "aspectRatio": "Auto",
    "resolution": "720p",
    "duration": "8s"
  }
}
```

### Response example

```json
{
  "taskId": "281e5b0…f39b9",
  "creditsCharged": 24
}
```

## Query Task

`GET https://you.bot/api/v1/task/{taskId}?model=veo-3-1-fast`

When `state` is `success`, the output is in `resultUrls`: `{ "state": "success", "resultUrls": [ ... ] }`. (Text models return inline in the create response.)

## Error Codes

| Code | Description |
|------|-------------|
| 200 | Request successful |
| 400 | Invalid request parameters |
| 401 | Authentication failed, check API Key |
| 402 | Insufficient account balance |
| 422 | Parameter validation failed |
| 429 | Request rate limit exceeded |
| 500 | Internal server error |