# FLUX.2 Klein 4B

> Very fast image generation and editing model. 4 steps distilled, sub-second inference for production and near real-time applications.

- **Provider**: replicate
- **Model ID**: black-forest-labs/flux-2-klein-4b
- **Category**: image_generation
- **Credits**: 2 per request
- **Pricing Type**: input_based

## API Endpoint

Base URL: https://api.core.today/v1

### Create Prediction
POST /predictions

### Get Status
GET /predictions/{job_id}

### Cancel
DELETE /predictions/{job_id}

## Authentication

Header: `X-API-Key: YOUR_API_KEY`

## Input Parameters

- `aspect_ratio` (string, optional): Aspect ratio for the generated image. Use 'match_input_image' to match the aspect ratio of the first input image. (Default: `1:1`; Options: `1:1`, `16:9`, `9:16`, `3:2`, `2:3`, `4:3`, `3:4`, `5:4`, `4:5`, `21:9`, `9:21`, `match_input_image`)
- `go_fast` (boolean, optional): Run faster predictions with additional optimizations. (Default: `False`)
- `output_format` (string, optional): Format of the output images (Default: `jpg`; Options: `webp`, `jpg`, `png`)
- `output_quality` (integer, optional): Quality when saving the output images, from 0 to 100. 100 is best quality, 0 is lowest quality. Not relevant for .png outputs. (Default: `95`; Range: min: 0, max: 100)
- `seed` (integer, optional): Random seed. Set for reproducible generation
- `prompt` (string, **required**): Text prompt for image generation.
- `output_megapixels` (string, optional): Resolution of the output image in megapixels (Default: `1`; Options: `0.25`, `0.5`, `1`, `2`, `4`)
- `disable_safety_checker` (boolean, optional): Disable safety checker for generated images. (Default: `False`)
- `images` (array, optional): List of input images for image-to-image generation. Maximum 5 images. Must be jpeg, png, gif, or webp. (Default: `[]`)

## Example Request

```json
{
  "model": "black-forest-labs/flux-2-klein-4b",
  "input": {
    "aspect_ratio": "1:1",
    "images": [],
    "output_megapixels": "1",
    "output_format": "jpg",
    "go_fast": false,
    "prompt": "A surreal underwater or cosmic garden scene with bioluminescent flora against a deep navy blue to black background. With large white text in the center \"FLUX.2 [klein] 4B\"",
    "output_quality": 95
  }
}
```

## Response Format

```json
{
  "job_id": "abc123",
  "status": "pending",
  "provider": "replicate",
  "model": "black-forest-labs/flux-schnell",
  "created_at": "2026-01-01T00:00:00Z",
  "result": null,
  "error": null
}
```

Status values: `pending`, `processing`, `completed`, `failed`, `cancelled`

## Usage Flow

1. POST /predictions with model and input → receive job_id
2. Poll GET /predictions/{job_id} until status is `completed` or `failed`
3. Result contains output URL(s) or data

## Output Type

url

## Tags

flux, flux-2, text-to-image, image-generation, image-editing, fast-generation, black-forest-labs

## Documentation

https://replicate.com/black-forest-labs/flux-2-klein-4b