Flux 2 Klein 4B - Image Generator

Compact 4 billion parameter image generation model by Black Forest Labs. 4-step distilled for sub-second inference, making it ideal for real-time applications, high-volume pipelines, and interactive products that need fast, quality image generation.

Endpoint

POSThttps://api.1min.ai/api/features

Request Headers

Field	Value
API-KEY	<api-key>
Content-Type	application/json

Parameters

Parameter	Type	Required	Description
type	string	Yes	Must be IMAGE_GENERATOR
model	string	Yes	Must be black-forest-labs/flux-2-klein-4b
promptObject	object	Yes	Configuration object containing all generation parameters

Prompt Object Parameters

Parameter	Type	Required	Description	Default
prompt	string	Yes	Text description of the image to generate	-
aspect_ratio	string	No	Image aspect ratio (1:1, 16:9, 9:16, 3:2, 2:3, 4:5, 5:4)	1:1
output_format	string	No	Output file format (webp, jpg, png)	webp
output_quality	number	No	Output image quality (0-100)	80
num_inference_steps	number	No	Number of inference steps (1-4)	4
go_fast	boolean	No	Enable fastest generation mode	true
megapixels	string	No	Output resolution in megapixels (0.25, 1)	1
disable_safety_checker	boolean	No	Disable built-in safety filtering	false
seed	number	No	Random seed for reproducibility	Random

Code Examples

cURL

curl --location 'https://api.1min.ai/api/features' \
--header 'API-KEY: <api-key>' \
--header 'Content-Type: application/json' \
--data '{
"type": "IMAGE_GENERATOR",
"model": "black-forest-labs/flux-2-klein-4b",
"promptObject": {
  "prompt": "A serene mountain lake at dawn, misty atmosphere, photorealistic",
  "aspect_ratio": "16:9",
  "num_inference_steps": 4,
  "go_fast": true,
  "megapixels": "1",
  "output_format": "webp",
  "output_quality": 80
}
}'

JavaScript

fetch('https://api.1min.ai/api/features', {
method: 'POST',
headers: {
  'Content-Type': 'application/json',
  'API-KEY': 'YOUR_API_KEY'
},
body: JSON.stringify({
  type: 'IMAGE_GENERATOR',
  model: 'black-forest-labs/flux-2-klein-4b',
  promptObject: {
    prompt: 'A serene mountain lake at dawn, misty atmosphere, photorealistic',
    aspect_ratio: '16:9',
    num_inference_steps: 4,
    go_fast: true,
    megapixels: '1',
    output_format: 'webp',
    output_quality: 80
  }
})
})

Python

import requests

url = "https://api.1min.ai/api/features"
headers = {
"Content-Type": "application/json",
"API-KEY": "YOUR_API_KEY"
}

data = {
"type": "IMAGE_GENERATOR",
"model": "black-forest-labs/flux-2-klein-4b",
"promptObject": {
  "prompt": "A serene mountain lake at dawn, misty atmosphere, photorealistic",
  "aspect_ratio": "16:9",
  "num_inference_steps": 4,
  "go_fast": True,
  "megapixels": "1",
  "output_format": "webp",
  "output_quality": 80
}
}

response = requests.post(url, headers=headers, json=data)

Interactive Playground

API Playground

GETPOSTPUTDELETEhttps://api.1min.ai/api/features

AI Model *Flux 2 Klein 4B - Black Forest Labs

Prompt *

Describe the image you want to generate

A serene mountain lake at dawn, misty atmosphere, photorealistic

Aspect Ratio 1:1 - Square16:9 - Widescreen9:16 - Vertical3:2 - Photography2:3 - Portrait4:5 - Instagram5:4 - Landscape

Inference Steps

Number of inference steps (1-4)

Megapixels 0.25 MP (~512×512)1 MP (~1024×1024)

Go Fast TrueFalse

Output Quality

Output image quality (0-100)

Seed

Random seed for reproducibility

Generated cURL Command:

curl -X POST "https://api.1min.ai/api/features" \
  -H "API-KEY: <your-api-key>" \
  -H "Content-Type: application/json" \
  -d '{
  "type": "IMAGE_GENERATOR",
  "model": "black-forest-labs/flux-2-klein-4b",
  "promptObject": {
    "prompt": "A serene mountain lake at dawn, misty atmosphere, photorealistic",
    "aspect_ratio": "16:9",
    "num_inference_steps": 4,
    "go_fast": true,
    "megapixels": "1",
    "output_format": "webp",
    "output_quality": 80
  }
}'

Response Format

{
"aiRecord": {
  "uuid": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "model": "black-forest-labs/flux-2-klein-4b",
  "type": "IMAGE_GENERATOR",
  "status": "SUCCESS",
  "createdAt": "2026-03-27T10:00:00.000Z",
  "aiRecordDetail": {
    "promptObject": {
      "prompt": "A serene mountain lake at dawn, misty atmosphere, photorealistic",
      "aspect_ratio": "16:9",
      "num_inference_steps": 4,
      "go_fast": true,
      "megapixels": "1",
      "output_format": "webp",
      "output_quality": 80
    },
    "resultObject": [
      "development/images/2026_03_27_10_00_01_001_mountain_lake.webp"
    ]
  },
  "temporaryUrl": "https://s3.us-east-1.amazonaws.com/asset.1min.ai/development/images/2026_03_27_10_00_01_001_mountain_lake.webp?..."
}
}

Use Cases

• Real-time Applications: Sub-second generation for interactive tools
• High-volume Pipelines: Cost-efficient bulk image generation
• Rapid Prototyping: Near-instant concept visualization
• Mobile Apps: Fast generation for resource-sensitive environments
• Creative Iteration: Quick multi-variation generation workflows

Notes

Speed-First Model

Flux 2 Klein 4B is optimized for speed with 4-step distillation. For higher fidelity output, consider Flux 2 Dev or Flux 2 Pro.