FLUX.1 Kontext [pro]

FLUX.1 Kontext [pro] image editing & generation model by Black Forest Labs via AnyFast API.

FLUX.1 Kontext [pro] is a context-aware image generation model from Black Forest Labs, available through AnyFast. It can generate new images from text prompts, or edit existing images based on text instructions. Both endpoints are synchronous — they return the generated image directly as base64-encoded data.

• Text-to-image — POST JSON to /v1/images/generations
• Image editing — POST multipart form data to /v1/images/edits

Key capabilities

• Image editing — Modify existing images with text instructions (e.g. “change the red car to blue”)
• Text-to-image — Generate images from text prompts
• Context-aware — Understands and preserves context from the reference image
• Reproducible — Use seed for deterministic generation

Quick example

Text-to-image

cURL

curl https://www.anyfast.ai/v1/images/generations \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "flux-1-kontext-pro",
    "prompt": "A cute baby polar bear",
    "size": "1024x1024"
  }'

import requests

response = requests.post(
    "https://www.anyfast.ai/v1/images/generations",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={
        "model": "flux-1-kontext-pro",
        "prompt": "A cute baby polar bear",
        "size": "1024x1024"
    }
)

result = response.json()
# result["data"][0]["b64_json"] contains the base64-encoded image

Image editing

cURL

curl https://www.anyfast.ai/v1/images/edits \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -F "model=flux-1-kontext-pro" \
  -F "image=@/path/to/photo.jpg" \
  -F "prompt=Change the background to a sunset beach" \
  -F "size=1024x1024"

import requests

response = requests.post(
    "https://www.anyfast.ai/v1/images/edits",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    files={"image": open("/path/to/photo.jpg", "rb")},
    data={
        "model": "flux-1-kontext-pro",
        "prompt": "Change the background to a sunset beach",
        "size": "1024x1024"
    }
)

result = response.json()
# result["data"][0]["b64_json"] contains the base64-encoded image

Text-to-image parameters

Parameter	Type	Required	Description
model	string	Yes	Must be flux-1-kontext-pro
prompt	string	Yes	Image description. ⚠️ Prompt must be in English
n	integer	No	Number of images. Only 1 is supported
size	string	No	Output size, e.g. 1024x1024
output_format	string	No	jpeg or png
seed	integer	No	Random seed for reproducibility

Image editing parameters

Parameter	Type	Required	Description
model	string	Yes	Must be flux-1-kontext-pro
image	file	Yes	Image file to edit (multipart upload)
prompt	string	Yes	Editing instructions. ⚠️ Prompt must be in English
n	integer	No	Number of images. Only 1 is supported
size	string	No	Output size, e.g. 1024x1024

Response

Field	Description
data[].b64_json	Base64-encoded image data
created	Unix timestamp

API Reference

View the interactive API playground for FLUX.1 Kontext [pro].