FLUX.2 [flex]

Text-to-Image • Black Forest Labs

black-forest-labs/flux-2-flex

• Third-party

FLUX.2 [flex] is Black Forest Labs' fine-grained control variant of FLUX.2 — exposes tunable inference steps, guidance, and prompt upsampling for typography-heavy and production workflows.

Usage

const response = await env.AI.run(
  'black-forest-labs/flux-2-flex',
  {
    prompt:
      "Samsung Galaxy S25 Ultra product advertisement, 'Ultra-strong titanium' headline, close-up of phone edge showing titanium frame, dark gradient background, clean minimalist tech aesthetic",
  },
)
console.log(response)

curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
  "model": "black-forest-labs/flux-2-flex",
  "input": {
    "prompt": "Samsung Galaxy S25 Ultra product advertisement, '\''Ultra-strong titanium'\'' headline, close-up of phone edge showing titanium frame, dark gradient background, clean minimalist tech aesthetic"
  }
}'

{
  "state": "Completed",
  "result": {
    "image": "https://examples.aig.cloudflare.com/black-forest-labs/flux-2-flex/typography-design.jpeg"
  },
  "gatewayMetadata": {
    "keySource": "Unified"
  }
}

Examples

<details>

<summary>High Detail Generation — Crank steps and guidance for maximum detail when latency is not the priority</summary>

const response = await env.AI.run(
  'black-forest-labs/flux-2-flex',
  {
    prompt: 'A detailed oil painting portrait of a Renaissance nobleman with intricate lace collar',
    guidance: 7.5,
    steps: 50,
  },
)
console.log(response)

curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
  "model": "black-forest-labs/flux-2-flex",
  "input": {
    "prompt": "A detailed oil painting portrait of a Renaissance nobleman with intricate lace collar",
    "guidance": 7.5,
    "steps": 50
  }
}'

{
  "state": "Completed",
  "result": {
    "image": "https://examples.aig.cloudflare.com/black-forest-labs/flux-2-flex/high-detail-generation.jpeg"
  },
  "gatewayMetadata": {
    "keySource": "Unified"
  }
}

</details>

<details>

<summary>Fast Draft — Fast draft with prompt upsampling disabled — preserves the literal prompt</summary>

const response = await env.AI.run(
  'black-forest-labs/flux-2-flex',
  { prompt: 'A simple line sketch of a mountain landscape', prompt_upsampling: false, steps: 10 },
)
console.log(response)

curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/run \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
  "model": "black-forest-labs/flux-2-flex",
  "input": {
    "prompt": "A simple line sketch of a mountain landscape",
    "prompt_upsampling": false,
    "steps": 10
  }
}'

{
  "state": "Completed",
  "result": {
    "image": "https://examples.aig.cloudflare.com/black-forest-labs/flux-2-flex/fast-draft.jpeg"
  },
  "gatewayMetadata": {
    "keySource": "Unified"
  }
}

</details>

Parameters

prompt

stringrequiredText prompt for image generation or editing.

seed

integerminimum: -9007199254740991maximum: 9007199254740991Optional seed for reproducible generation.

width

integerminimum: 64maximum: 9007199254740991Width of the generated image in pixels (minimum 64). Omit to let BFL pick.

height

integerminimum: 64maximum: 9007199254740991Height of the generated image in pixels (minimum 64). Omit to let BFL pick.

safety_tolerance

integerminimum: 0maximum: 5Tolerance for input/output moderation. 0 is the strictest, 5 the most permissive. Defaults to 2.

output_format

stringenum: jpeg, png, webpOutput image format. Defaults to jpeg.

▶input_images[]

arraymaxItems: 8Up to 8 reference images for editing or multi-image composition. Each entry is an HTTPS URL or a data:image/...;base64,... URI.

prompt_upsampling

booleanWhether BFL should expand short prompts before generation. Defaults to true on flex.

guidance

numberminimum: 1.5maximum: 10Classifier-free guidance scale (1.5–10). Higher values follow the prompt more strictly at the cost of realism.

steps

integerminimum: 1maximum: 50Number of denoising steps (1–50). Higher steps yield more detail at the cost of latency.

image

stringformat: uriURL to the generated image

API Schemas (Raw)

Input Open Download

Output Open Download

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description: FLUX.2 [max] is Black Forest Labs' highest-quality image model — top editing consistency, strongest prompt following, and grounding search for visualizations of real-time information. title: FLUX.2 [max] image: https://developers.cloudflare.com/og-docs.png

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