black-forest-labs/flux-2-dev/text-to-image

Text to Image

Black Forest Labs FLUX.2 Dev is the open-weight FLUX.2 model, pairing strong realism and crisp text with full control over quality and speed. Tune guidance from 0 to 20 and steps from 4 to 50, add prompt expansion or acceleration, and generate up to 4 images per call.

Try it Get API keyOpenAPI llms.txt

Prompt *

Image size

More settings (7)

Acceleration

Enable prompt expansion

Guidance Scale

Number of Images

Number of inference steps

Output Format

Seed

ResultExampleSign in to try

$0.012 / megapixel · billed by each image's actual pixels

Example — generated from this input

A cozy independent bookshop window at dusk, warm light spilling onto a quiet street. Neat stacks of colorful hardcover books, a sleeping tabby cat on a velvet cushion, trailing plants, and a hand-lettered wooden sign in the window that reads "NEW ARRIVALS" in cream paint. Realistic photograph, soft reflections on the glass, crisp lettering, rich detail.

Pricing

Unit price $0.012 / megapixel

Billed by the actual pixels of each image; larger sizes and more images cost more. 1024×1024 is about 1 megapixel.

Typically about $0.012 per image at default settings.

Each request temporarily reserves $0.012; you are charged for actual usage, usually within a minute: any unused amount is released and any usage above it is charged to your balance, even if that takes it below zero; while your balance is below zero, new requests are paused until a top-up covers it.

Failed generations are not charged.

API

Submit generation requests with this model ID.

POST/v1/model-tasks

black-forest-labs/flux-2-dev/text-to-image

Request body

{
  "model": "black-forest-labs/flux-2-dev/text-to-image",
  "input": {
    "prompt": "A cozy independent bookshop window at dusk, warm light spilling onto a quiet street. Neat stacks of colorful hardcover books, a sleeping tabby cat on a velvet cushion, trailing plants, and a hand-lettered wooden sign in the window that reads \"NEW ARRIVALS\" in cream paint. Realistic photograph, soft reflections on the glass, crisp lettering, rich detail.",
    "acceleration": "regular",
    "enable_prompt_expansion": false,
    "guidance_scale": 2.5,
    "image_size": "landscape_4_3",
    "num_images": 1,
    "num_inference_steps": 28,
    "output_format": "png"
  }
}

Input schema

Parameter	Type	Requirement	Default
prompt	string	Required	—
acceleration	string	Optional	regular
enable_prompt_expansion	boolean	Optional	false
guidance_scale	number	Optional	2.5
image_size	object \| string	Optional	landscape_4_3
num_images	integer	Optional	1
num_inference_steps	integer	Optional	28
output_format	string	Optional	png
seed	integer	Optional	—

Response

The API returns a result or a pollable asynchronous task. See the examples and Schema below for the response mode and result fields.

Asynchronous task

Submit response

HTTP 202

/v1/model-tasksapplication/json

{
  "id": "task_example",
  "model": "black-forest-labs/flux-2-dev/text-to-image",
  "status": "queued"
}

Status response

HTTP 200

/v1/model-tasks/{id}application/json

{
  "id": "task_example",
  "model": "black-forest-labs/flux-2-dev/text-to-image",
  "status": "completed",
  "output": {
    "images": [
      {
        "url": "https://api.musespan.com/v1/model-tasks/task_example/artifacts/0"
      }
    ]
  }
}

File download

HTTP 200

/v1/model-tasks/{id}/artifacts/{index}Generated image (e.g. image/png)

When the task completes, file URLs in output point to this endpoint, numbered from 0. Send the same API key (Authorization header) when downloading.

Error response

HTTP 400

/v1/model-tasksapplication/json

{
  "error": {
    "code": "invalid_input",
    "message": "The input does not match this model's input schema. Check the model's API documentation.",
    "type": "invalid_request_error"
  }
}

Code examples

Async submission returns a task ID. Poll until status is completed, then retrieve the generated content from the result. Get your API key in the console.

# Use a new directory for each new generation. Rerunning here continues this task.
set -eu
test -s model-task-id.txt || python3 -c "import uuid; print(uuid.uuid4())" > model-task-id.txt
REQUEST_ID=$(cat model-task-id.txt)
# Idempotent: resending the same bytes with the same ID never charges twice.
curl --fail-with-body --retry 3 --retry-connrefused --request POST 'https://api.musespan.com/v1/model-tasks' \
  --header "Authorization: Bearer $MUSESPAN_API_KEY" \
  --header "X-Request-Id: $REQUEST_ID" \
  --header "Content-Type: application/json" \
  --data '{"model":"black-forest-labs/flux-2-dev/text-to-image","input":{"prompt":"A cozy independent bookshop window at dusk, warm light spilling onto a quiet street. Neat stacks of colorful hardcover books, a sleeping tabby cat on a velvet cushion, trailing plants, and a hand-lettered wooden sign in the window that reads \"NEW ARRIVALS\" in cream paint. Realistic photograph, soft reflections on the glass, crisp lettering, rich detail.","acceleration":"regular","enable_prompt_expansion":false,"guidance_scale":2.5,"image_size":"landscape_4_3","num_images":1,"num_inference_steps":28,"output_format":"png"}}'
# Poll every 5 seconds for up to 25 minutes until status is completed or failed.
# Still queued (with queue_position) 5 minutes after submission: failed with queue_timeout, not charged.
# No result 15 minutes after acceptance (or no confirmation 15 minutes after submission): failed with generation_timeout, not charged.
# Any failure is final: generate again in a new directory (a new X-Request-Id).
# A 404 means the POST did not arrive: rerun this script to resend it with the same ID.
curl --fail-with-body 'https://api.musespan.com/v1/model-tasks/'"$REQUEST_ID"'' --header "Authorization: Bearer $MUSESPAN_API_KEY"