# FLUX.1 [dev]

> Black Forest Labs' 12-billion parameter flow transformer for high-quality text-to-image generation, suitable for personal and commercial use with streaming support

## Quick Reference

- Model ID: flux.1-dev
- Creator: Black Forest Labs
- Status: active
- Family: flux.1
- Base URL: https://api.lumenfall.ai/openai/v1

## Specifications

- Max Resolution: 2048x2048
- Input Modalities: text
- Output Modalities: image
- Supported Modes: Text to Image, Image Edit

## API Parameters

The compiled parameter schema for this model is available via the API: `GET /v1/models/flux.1-dev?schema=true`.

### Core Parameters

- `prompt` (string) — REQUIRED: Text prompt for image generation. Modes: Text to Image, Image Edit
- `seed` (integer): Random seed for reproducibility. Modes: Text to Image, Image Edit

### Size & Layout

- `size` (string): Image dimensions as WxH pixels (e.g. "1024x1024") or aspect ratio (e.g. "16:9"). Values: 1563x670, 670x1564, 1365x768, 768x1365, 1254x836, 836x1254, 887x1182, 1024x1024, 1145x916, 916x1145, 1183x887. Modes: Text to Image, Image Edit
- `aspect_ratio` (string): Aspect ratio of the output image (e.g. "16:9", "1:1"). Values: 9:21, 9:16, 2:3, 3:4, 4:5, 1:1, 5:4, 4:3, 3:2, 16:9, 21:9. Modes: Text to Image, Image Edit
- `resolution` (string): Output resolution tier (e.g. "1K", "4K"). Values: 1K. Modes: Text to Image, Image Edit

### Media Inputs

- `image` (file) — REQUIRED: Input image(s) to edit. Modes: Image Edit

### Output & Format

- `response_format` (string): How to return the image. Default: url. Values: url, b64_json. Modes: Text to Image, Image Edit
- `output_format` (string): Output image format. Values: png, jpeg, gif, webp, avif. Modes: Text to Image, Image Edit
- `output_compression` (integer): Compression level for lossy formats (JPEG, WebP, AVIF). Modes: Text to Image, Image Edit
- `n` (integer): Number of images to generate. Default: 1. Modes: Text to Image, Image Edit

### Additional Parameters

- `cfg_scale` (number): Classifier-free guidance scale — higher values stick more closely to the prompt. Modes: Text to Image, Image Edit
- `strength` (number): How much to transform the input image: 0 keeps it unchanged, 1 fully regenerates from the prompt. Modes: Image Edit
- `acceleration` (string): The speed of the generation. The higher the speed, the faster the generation.. Values: high, none, regular. Modes: Text to Image. Only available via fal
- `disable_safety_checker` (boolean): Disable safety checker for generated images.. Modes: Text to Image, Image Edit. Only available via replicate
- `enable_safety_checker` (boolean): If set to true, the safety checker will be enabled.. Modes: Text to Image. Only available via fal
- `go_fast` (boolean): Run faster predictions with model optimized for speed (currently fp8 quantized); disable to run in original bf16. Note that outputs will not be deterministic when this is enabled, even if you set a seed.. Modes: Text to Image, Image Edit. Only available via replicate
- `megapixels` (string): Approximate number of megapixels for generated image. Values: 0.25, 1. Modes: Text to Image, Image Edit. Only available via replicate
- `num_inference_steps` (integer): The number of inference steps to perform.. Modes: Text to Image, Image Edit
- `output_quality` (integer): Quality when saving the output images, from 0 to 100. 100 is best quality, 0 is lowest quality. Not relevant for .png outputs. Modes: Text to Image, Image Edit. Only available via replicate
- `sync_mode` (boolean): If `True`, the media will be returned as a data URI and the output data won't be available in the request history.. Modes: Text to Image. Only available via fal


## Model Identifiers

- Primary Slug: flux.1-dev
- Aliases: flux-dev


## Tags

image-generation, text-to-image, open-weights

## Available Providers

### fal.ai

- Config Key: fal/flux.1-dev
- Provider Model ID: fal-ai/flux/dev
- Pricing: $0.025/image
  - Source: https://fal.ai/models/fal-ai/flux/dev

### Replicate

- Config Key: replicate/flux.1-dev
- Provider Model ID: black-forest-labs/flux-dev
- Pricing: $0.025/image
  - Source: https://replicate.com/black-forest-labs/flux-dev


## Image Gallery

3 images available for this model. Browse all at https://lumenfall.ai/models/black-forest-labs/flux.1-dev/gallery

### Curated Examples

- [Cinematic wide shot of a high-end, minimalist boutique storefront at dusk. The shop’s large glass...](https://assets.lumenfall.ai/6tUGW58CGpVGC5P41-k4l0xeKOC03qmvHvdDfjEiKAI/rs:fit:1500:1500/plain/gs://lumenfall-prod-assets/um7rgf8ve8kzrvbdqin92quwrke0@jpeg)
- [A hyper-realistic close-up of a weathered, sun-drenched pottery workshop in Tuscany. Rough-textur...](https://assets.lumenfall.ai/xO0MKCyDW6IjUUKQbdFDBtu9Ol3KQzOLI4GK2I11NDc/rs:fit:1500:1500/plain/gs://lumenfall-prod-assets/eyy30134ubr6wqq0917yb97y2oqr@jpeg)
- [A cozy street-side flower shop with a slate chalkboard sign out front that reads "FRESH BLOOMS & ...](https://assets.lumenfall.ai/6h7v6vNITQS26hnKA033SZtk0U3gGBtR0YwtLV1vzjg/rs:fit:1500:1500/plain/gs://lumenfall-prod-assets/obf6k61cijb8nrh2ws4pbfc0s03p@jpeg)

## Example Prompt

The following prompt was used to generate an example image in our playground:

A cozy street-side flower shop with a slate chalkboard sign out front that reads "FRESH BLOOMS & WILD BOUQUETS" in elegant chalk calligraphy. In the soft-focus background, a calm capybara sits patiently on the sidewalk near a bicycle.

## Code Examples

### Text to Image (/v1/images/generations)

#### cURL

curl -X POST \
  https://api.lumenfall.ai/openai/v1/images/generations \
  -H "Authorization: Bearer $LUMENFALL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "flux.1-dev",
    "prompt": "",
    "size": "1024x1024"
  }'

# Response:
# { "created": 1234567890, "data": [{ "url": "https://...", "revised_prompt": "..." }] }

#### JavaScript

import OpenAI from 'openai';

const client = new OpenAI({
  apiKey: 'YOUR_API_KEY',
  baseURL: 'https://api.lumenfall.ai/openai/v1'
});

const response = await client.images.generate({
  model: 'flux.1-dev',
  prompt: '',
  size: '1024x1024'
});

// { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }
console.log(response.data[0].url);

#### Python

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://api.lumenfall.ai/openai/v1"
)

response = client.images.generate(
    model="flux.1-dev",
    prompt="",
    size="1024x1024"
)

# { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }
print(response.data[0].url)

### Image Edit (/v1/images/edits)

#### cURL

curl -X POST \
  https://api.lumenfall.ai/openai/v1/images/edits \
  -H "Authorization: Bearer $LUMENFALL_API_KEY" \
  -F "model=flux.1-dev" \
  -F "image=@source.png" \
  -F "prompt=Add a starry night sky to this image" \
  -F "size=1024x1024"

# Response:
# { "created": 1234567890, "data": [{ "url": "https://...", "revised_prompt": "..." }] }

#### JavaScript

import OpenAI from 'openai';
import fs from 'fs';

const client = new OpenAI({
  apiKey: 'YOUR_API_KEY',
  baseURL: 'https://api.lumenfall.ai/openai/v1'
});

const response = await client.images.edit({
  model: 'flux.1-dev',
  image: fs.createReadStream('source.png'),
  prompt: 'Add a starry night sky to this image',
  size: '1024x1024'
});

// { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }
console.log(response.data[0].url);

#### Python

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_API_KEY",
    base_url="https://api.lumenfall.ai/openai/v1"
)

response = client.images.edit(
    model="flux.1-dev",
    image=open("source.png", "rb"),
    prompt="Add a starry night sky to this image",
    size="1024x1024"
)

# { created: 1234567890, data: [{ url: "https://...", revised_prompt: "..." }] }
print(response.data[0].url)


## About

## Overview
FLUX.1 [dev] is a 12-billion parameter text-to-image synthesis model developed by Black Forest Labs. As an open-weight model derived from the FLUX.1 [pro] architecture, it is designed for high-fidelity image generation while remaining accessible for non-commercial development. It is distinguished by its use of flow matching, which allows it to generate images with higher composition quality and structural integrity than traditional diffusion-based models of similar size.

## Strengths
*   **Precise Text Rendering:** The model excels at following complex prompts requiring the inclusion of specific text, exhibiting high character accuracy and legibility in generated signs, labels, and documents.
*   **Anatomical Accuracy:** It shows a significant reduction in common AI artifacts, such as distorted hands or inconsistent limb counts, producing more anatomically correct human figures.
*   **Prompt Adherence:** The architecture is highly responsive to detailed, long-form descriptions, maintaining high fidelity to nuanced instructions regarding lighting, camera angles, and object placement.
*   **Visual Variety:** It is capable of generating a wide range of styles, from photorealistic portraits to stylized digital art, without requiring extensive LoRA fine-tuning for basic aesthetic changes.

## Limitations
*   **Hardware Requirements:** With 12 billion parameters, the model is computationally heavy; running it locally requires substantial VRAM (typically 24GB or more) compared to smaller models like Stable Diffusion XL.
*   **Inference Speed:** While it supports streaming, the generation process is inherently slower than "schnell" or distilled versions of the same family due to the higher step count required for optimal results.
*   **Licensing Constraints:** Unlike the [schnell] variant, the [dev] model is released under a non-commercial license, which may limit its direct use in some production environments without a commercial agreement.

## Technical Background
FLUX.1 [dev] is built on a flow-based transformer architecture. Rather than relying on standard latent diffusion, it utilizes flow matching—a method that learns a vector field to map a simple noise distribution to the target data distribution. This approach, combined with its high parameter count, allows the model to capture more complex spatial relationships and finer details during the sampling process.

## Best For
This model is best suited for developers building high-end creative tools, designers requiring precise typography within images, and researchers exploring the limits of flow-matching models. It is an ideal choice for tasks where image quality and prompt accuracy are more critical than raw generation speed. FLUX.1 [dev] is available for testing and integration through Lumenfall’s unified API and interactive playground.

## Frequently Asked Questions

### How much does FLUX.1 [dev] cost?

FLUX.1 [dev] starts at $0.025 per image through Lumenfall. Pricing varies by provider. Lumenfall does not add any markup to provider pricing.

### How do I use FLUX.1 [dev] via API?

You can use FLUX.1 [dev] through Lumenfall's OpenAI-compatible API. Send requests to the unified endpoint with model ID "flux.1-dev". Code examples are available in Python, JavaScript, and cURL.

### Which providers offer FLUX.1 [dev]?

FLUX.1 [dev] is available through fal.ai and Replicate on Lumenfall. Lumenfall automatically routes requests to the best available provider.

### What is the maximum resolution for FLUX.1 [dev]?

FLUX.1 [dev] supports images up to 2048x2048 resolution.

## Links

- Model Page: https://lumenfall.ai/models/black-forest-labs/flux.1-dev
- About: https://lumenfall.ai/models/black-forest-labs/flux.1-dev/about
- Providers, Pricing & Performance: https://lumenfall.ai/models/black-forest-labs/flux.1-dev/providers
- API Reference: https://lumenfall.ai/models/black-forest-labs/flux.1-dev/api
- Benchmarks: https://lumenfall.ai/models/black-forest-labs/flux.1-dev/benchmarks
- Use Cases: https://lumenfall.ai/models/black-forest-labs/flux.1-dev/use-cases
- Gallery: https://lumenfall.ai/models/black-forest-labs/flux.1-dev/gallery
- Playground: https://lumenfall.ai/playground?model=flux.1-dev
- API Documentation: https://docs.lumenfall.ai