FLUX.2 [flex]

FLUX.2 [flex] text-to-image model by Black Forest Labs via AnyFast API.

FLUX.2 [flex] is a highly configurable text-to-image generation model from Black Forest Labs, available through AnyFast. It offers fine-grained control over inference steps and guidance scale for design experts. The API is synchronous — it returns the generated image directly as base64-encoded data.

Key capabilities

• Text-to-image — Generate images from text descriptions
• Inference steps control — Adjust sampling steps (1–50) for speed vs. fidelity tradeoff
• Guidance scale — Fine-tune prompt adherence (1.5–10)
• High resolution — Supports up to 4MP output resolution
• Reproducible — Use seed for deterministic generation

Quick example

cURL

curl https://www.anyfast.ai/v1/images/generations \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "flux-2-flex",
    "prompt": "A cute baby polar bear",
    "size": "1024x1024",
    "inference_steps": 30,
    "guidance_scale": 7.5
  }'

import requests

response = requests.post(
    "https://www.anyfast.ai/v1/images/generations",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={
        "model": "flux-2-flex",
        "prompt": "A cute baby polar bear",
        "size": "1024x1024",
        "inference_steps": 30,
        "guidance_scale": 7.5
    }
)

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

Parameters

Parameter	Type	Required	Description
model	string	Yes	Must be flux-2-flex
prompt	string	Yes	Text description of the image
n	integer	No	Number of images (1–4). Default: 1
size	string	No	Output size, e.g. 1024x1024. Supports up to 4MP
inference_steps	integer	No	Sampling steps (1–50). Low (6–20) for fast prototyping, high (40–50) for max fidelity
guidance_scale	number	No	Guidance scale (1.5–10). Higher = more prompt-faithful
output_format	string	No	jpeg or png
seed	integer	No	Random seed for reproducibility

Response

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

API Reference

View the interactive API playground for FLUX.2 [flex].