MuseSpan
Black Forest Labs

black-forest-labs/flux-3/text-to-image

Text to Image

Black Forest Labs FLUX 3 is the newest FLUX model, built for detailed, well-composed images with precise layout and cleaner in-image text. Render in native 2K or 4K, or as fast 512 and 768 square drafts, across 14 aspect ratios plus auto, with optional prompt expansion for packaging, ads and editorial art.

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$0.024 / megapixel · billed by each image's actual pixels

FLUX 3 Text to Image example
Example — generated from this input

Clean studio product photo of three craft coffee bags standing side by side on a light oak shelf against a warm plaster wall. The bags are sage green, terracotta and cream, each with a minimalist label in crisp black type reading "MORNING RIDGE", "DESERT BLOOM" and "NORTH HARBOR", with a smaller line underneath each reading "Single Origin". Soft morning light, gentle shadows, precise centered composition, sharp packaging detail.

Pricing

Unit price $0.024 / megapixel

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

Typically about $0.024 per request at default settings.

Each request temporarily reserves $0.024; 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-3/text-to-image
Request body
{
  "model": "black-forest-labs/flux-3/text-to-image",
  "input": {
    "prompt": "Clean studio product photo of three craft coffee bags standing side by side on a light oak shelf against a warm plaster wall. The bags are sage green, terracotta and cream, each with a minimalist label in crisp black type reading \"MORNING RIDGE\", \"DESERT BLOOM\" and \"NORTH HARBOR\", with a smaller line underneath each reading \"Single Origin\". Soft morning light, gentle shadows, precise centered composition, sharp packaging detail.",
    "aspect_ratio": "auto",
    "enable_prompt_expansion": false,
    "output_format": "jpeg",
    "resolution": "1k",
    "version": "latest"
  }
}

Input schema

ParameterTypeRequirementDefault
promptstringRequired—
aspect_ratiostringOptionalauto
enable_prompt_expansionbooleanOptionalfalse
output_formatstringOptionaljpeg
resolutionstringOptional1k
versionstringOptionallatest

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-3/text-to-image",
  "status": "queued"
}
Status response
HTTP 200
/v1/model-tasks/{id}application/json
{
  "id": "task_example",
  "model": "black-forest-labs/flux-3/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: $REQUEST_ID" \
  --header "Content-Type: application/json" \
  --data '{"model":"black-forest-labs/flux-3/text-to-image","input":{"prompt":"Clean studio product photo of three craft coffee bags standing side by side on a light oak shelf against a warm plaster wall. The bags are sage green, terracotta and cream, each with a minimalist label in crisp black type reading \"MORNING RIDGE\", \"DESERT BLOOM\" and \"NORTH HARBOR\", with a smaller line underneath each reading \"Single Origin\". Soft morning light, gentle shadows, precise centered composition, sharp packaging detail.","aspect_ratio":"auto","enable_prompt_expansion":false,"output_format":"jpeg","resolution":"1k","version":"latest"}}'
# Poll every 5 seconds for up to 25 minutes until status is completed or failed.
# Still queued (with queue_position) 5 minutes after submission: failed with queue_timeout, not charged.
# No result 15 minutes after acceptance (or no confirmation 15 minutes after submission): failed with generation_timeout, not charged.
# Any failure is final: generate again in a new directory (a new X-Request-Id).
# A 404 means the POST did not arrive: rerun this script to resend it with the same ID.
curl --fail-with-body 'https://api.musespan.com/v1/model-tasks/'"$REQUEST_ID"'' --header "Authorization: Bearer $MUSESPAN_API_KEY"