Flux Kontext Pro API

Complete API reference for Flux Kontext Pro with multi-image context understanding.

Model Overview

Quick Comparison

Supported Aspect Ratios

Both modes support 9 aspect ratios:

• 1:1, 16:9, 9:16, 3:2, 2:3, 4:3, 3:4, 21:9, 9:21

Cost

Flux Kontext Pro (Text-to-Image)

Endpoint

POST /api/v1/image/task

Authentication

Authorization: Bearer YOUR_API_KEY

Request Parameters

Required

Note: The width:height ratio must be one of: "1:1", "16:9", "9:16", "3:2", "2:3", "4:3", "3:4", "21:9", "9:21"

Example Request

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const response = await fetch('https://api.flaq.ai/api/v1/image/task', {
  method: 'POST',
  headers: {
    'Authorization': 'Bearer YOUR_API_KEY',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    model_name: 'flux-kontext-pro',
    prompt: 'A serene mountain landscape at sunset',
    width: 16,
    height: 9
  })
});

const { data } = await response.json();
const taskId = data.task_id;

// Poll for results
const pollResponse = await fetch(
  `https://api.flaq.ai/api/v1/image/${taskId}`,
  {
    headers: { 'Authorization': 'Bearer YOUR_API_KEY' }
  }
);

const result = await pollResponse.json();
console.log(result.data.task_result.images[0].url);

Flux Kontext Pro (Image-to-Image)

Endpoint

POST /api/v1/image/task

Request Parameters

Required

Note: The width:height ratio must be one of: "1:1", "16:9", "9:16", "3:2", "2:3", "4:3", "3:4", "21:9", "9:21"

Single Image Edit Example

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{
  model_name: 'flux-kontext-pro',
  prompt: 'Transform this photo into a watercolor painting',
  width: 16,
  height: 9,
  image_url_list: ['https://example.com/image.jpg']
}

Multi-Image Composition Example

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{
  model_name: 'flux-kontext-pro',
  prompt: 'Combine these images into a cohesive landscape scene',
  width: 16,
  height: 9,
  image_url_list: ['https://example.com/image1.jpg', 'https://example.com/image2.jpg', 'https://example.com/image3.jpg']
}

Response Format

Initial Response

Both modes return a task_id for polling:

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{
  "code": 0,
  "data": {
    "task_id": "{task_id}",
    "task_status": "submitted",
    "response_url": "https://api.flaq.ai/api/v1/image/{task_id}"
  },
  "message": "success"
}

Polling Response

Poll /api/v1/image/{taskId} to check status:

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{
  "code": 0,
  "data": {
    "task_id": "{task_id}",
    "task_status": "succeed",
    "task_status_msg": null,
    "response_url": "https://api.flaq.ai/api/v1/image/{task_id}",
    "task_result": {
      "credit": 0.04,
      "images": [
        {
          "url": "https://example.com/generated-image.jpeg"
        }
      ]
    }
  },
  "message": "success"
}

Status Values

• submitted: Task accepted
• processing: Generation in progress
• succeed: Generation completed successfully
• failed: Generation failed

Error Handling

Common Errors

Invalid Aspect Ratio

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{
  "code": 400,
  "message": "Ratio must be one of: 1:1, 16:9, 9:16, 3:2, 2:3, 4:3, 3:4, 21:9, 9:21"
}

Missing Image URL (Image-to-Image Mode)

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{
  "code": 400,
  "message": "image_url_list is required for flux-kontext-pro"
}

Too Many Images

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{
  "code": 400,
  "message": "Maximum 5 images allowed"
}

Best Practices

Text-to-Image Tips

1. Be Specific: Include subject, style, lighting, composition details
2. Aspect Ratio Selection: Choose ratio based on your use case (16:9 for web, 9:16 for mobile)
3. Prompt Quality: More detailed prompts generally produce better results
4. Efficient Polling: Check status every 2-3 seconds

Image-to-Image Tips

1. Clear Instructions: Be specific about the desired transformation
2. Multi-Image Context: Can combine up to 5 images for context-aware generation
3. Prompt Guidance: Describe the desired outcome, not just the changes
4. Image Quality: Higher quality input images produce better results

Example Use Cases

Product Photography

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{
  model_name: 'flux-kontext-pro',
  prompt: 'Professional product shot of luxury watch on marble surface',
  width: 4,
  height: 3
}

Multi-Image Collage

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{
  model_name: 'flux-kontext-pro',
  image_url_list: ['photo1.jpg', 'photo2.jpg', 'photo3.jpg'],
  prompt: 'Create a seamless collage with these vacation photos',
  width: 16,
  height: 9
}

Style Transfer

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{
  model_name: 'flux-kontext-pro',
  image_url_list: ['photo.jpg'],
  prompt: 'Transform into impressionist painting style',
  width: 1,
  height: 1
}