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POST
/
flux
/
v1
/
flux-kontext-pro
flux-kontext-pro (submit task)
curl --request POST \
  --url https://api.example.com/flux/v1/flux-kontext-pro
Flux’s official format for the submit task API. 
curl --location --request POST 'https://gptproto.com/flux/v1/flux-kontext-pro' \
--header 'Authorization: YOUR_API_KEY' \
--header 'Content-Type: application/json' \
--data-raw '{
  "prompt": "ein fantastisches bild",
  "input_image": "base64_encoded_image",
  "input_image_2": "base64_encoded_image",
  "input_image_3": "base64_encoded_image",
  "input_image_4": "base64_encoded_image",
  "seed": 42,
  "aspect_ratio": "21:9",
  "output_format": "jpeg",
  "webhook_url": "https://your-webhook-url.com",
  "webhook_secret": "your_secret",
  "prompt_upsampling": false,
  "safety_tolerance": 2
}'

{
  "error": {
    "message": "Invalid signature",
    "type": "401"
  }
}

​
Request Body

ParameterTypeRequiredDefaultDescription
promptstring✅ Yes-The text prompt describing the image to generate
input_imagestring✅ Yes-Base64 encoded input image (first image)
input_image_2string❌ No-Base64 encoded input image (second image)
input_image_3string❌ No-Base64 encoded input image (third image)
input_image_4string❌ No-Base64 encoded input image (fourth image)
seedinteger❌ No-Random seed for reproducible generation
aspect_ratiostring❌ No16:9Aspect ratio of the generated image. Options: 16:9, 9:16, 1:1, 4:3, 3:4, 21:9
output_formatstring❌ NojpegOutput image format. Options: jpeg, png, webp
webhook_urlstring❌ No-URL to receive webhook notifications when the task is completed
webhook_secretstring❌ No-Secret key for webhook verification
prompt_upsamplingboolean❌ NofalseWhether to enhance the prompt automatically
safety_toleranceinteger❌ No2Safety tolerance level for content filtering. Range: 0-6 (0 = strict, 6 = permissive)