Black Forest LabsTutorial

How to Use FLUX.2 [max] API

A step-by-step FLUX.2 [max] API tutorial with Python, Node.js and cURL: submit a text to image job, poll it or receive a webhook, and download the image. The example below costs $0.062.

Endpoints: 1; Text to Image
Example request: $0.062; Text to Image
Languages: 3; Python · Node.js · cURL
Failed runs: $0; refunded automatically

Try in Studio Call the API

Get an API key

Create an account, add credits (from $10) and create a key in Dashboard → API keys. Store it as CHEAPERGEN_API_KEY on your server. Every request sends it as a bearer token.

How to get a FLUX.2 [max] API key

Choose a FLUX.2 [max] endpoint

Each task has its own endpoint. All of them take a JSON body and return a generation you can poll.

FLUX.2 [max] API endpoints, required inputs and prices
Task	Endpoint	Required	From
Text to Image	bfl/flux-2-max/text-to-image	prompt	$0.0616/image

Submit a text to image job

This program submits the job, polls every 3 seconds until it finishes and prints the image URL. Swap the prompt and settings for your own.

import os, time, requests

API = "https://cheapergen.com/api/v1"
headers = {"Authorization": f"Bearer {os.environ['CHEAPERGEN_API_KEY']}"}

# 1. Submit the job
job = requests.post(f"{API}/run/bfl/flux-2-max/text-to-image", headers=headers, json={
    "prompt": "Editorial photo of a ceramic vase with dried flowers on a linen-covered table, soft north light, film grain",
    "aspect_ratio": "1:1",
    "resolution": "1MP"
}).json()

# 2. Poll until it finishes (or pass "webhook_url" and skip polling)
while job["status"] in ("queued", "running"):
    time.sleep(3)
    job = requests.get(f"{API}/generations/{job['id']}", headers=headers).json()

print(job["status"], job["output"]["images"][0]["url"] if job["status"] == "succeeded" else job["error"])

const API = "https://cheapergen.com/api/v1";
const headers = {
  Authorization: `Bearer ${process.env.CHEAPERGEN_API_KEY}`,
  "Content-Type": "application/json",
};

// 1. Submit the job
let job = await fetch(`${API}/run/bfl/flux-2-max/text-to-image`, {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "Editorial photo of a ceramic vase with dried flowers on a linen-covered table, soft north light, film grain",
    "aspect_ratio": "1:1",
    "resolution": "1MP"
  }),
}).then((r) => r.json());

// 2. Poll until it finishes (or pass webhook_url and skip polling)
while (job.status === "queued" || job.status === "running") {
  await new Promise((r) => setTimeout(r, 3000));
  job = await fetch(`${API}/generations/${job.id}`, { headers }).then((r) => r.json());
}

console.log(job.status === "succeeded" ? job.output.images[0].url : job.error);

curl -X POST https://cheapergen.com/api/v1/run/bfl/flux-2-max/text-to-image \
  -H "Authorization: Bearer $CHEAPERGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "prompt": "Editorial photo of a ceramic vase with dried flowers on a linen-covered table, soft north light, film grain",
  "aspect_ratio": "1:1",
  "resolution": "1MP"
}'

Set the parameters that matter

The settings for bfl/flux-2-max/text-to-image, with what each one does to the price.

FLUX.2 [max] Text to Image parameters and their effect on price
Parameter	Type · default	What it does	Price effect
aspect_ratio	string (enum) · 1:1	Output image shape. 1:1 · 4:3 · 3:4 · 16:9 · 9:16 · 3:2 · 2:3 · 21:9 · 9:21	Yes
resolution	string (enum) · 1MP	Output size in megapixels (1 MP ≈ 1024×1024). FLUX.2 is billed per megapixel. 1MP · 2MP · 3MP · 4MP	1 MP: $0.0616/image 2 MP: $0.088/image 3 MP: $0.1144/image 4 MP: $0.1408/image
prompt_upsampling	boolean · false	Let the model expand and rewrite the prompt before generating.	None
seed	integer	Use the same seed and settings to reproduce a result. Leave empty for random.	None

Get the result

A job moves from queued to running to succeeded, failed or canceled. Poll GET /api/v1/generations/{id}, or pass webhook_url and we POST the result to you. Download the output and store it yourself.

200 — succeeded

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "bfl/flux-2-max",
  "endpoint": "bfl/flux-2-max/text-to-image",
  "mode": "text-to-image",
  "status": "succeeded",
  "input": {
    "prompt": "Editorial photo of a ceramic vase with dried flowers on a linen-covered table, soft north light, film grain",
    "aspect_ratio": "1:1",
    "resolution": "1MP"
  },
  "output": {
    "images": [
      {
        "url": "https://cdn.cheapergen.com/outputs/gen_8c2Q-0.png",
        "content_type": "image/png",
        "width": 2048,
        "height": 2048
      }
    ]
  },
  "error": null,
  "cost": {
    "amount_usd": 0.2255,
    "currency": "usd",
    "estimated": false,
    "official_usd": 0.264,
    "saved_usd": 0.0385
  },
  "source": "api",
  "created_at": "2026-10-15T09:21:04Z",
  "started_at": "2026-10-15T09:21:06Z",
  "completed_at": "2026-10-15T09:22:31Z"
}

Verify webhook signatures

Price a request before you run it

The quote endpoint is free and needs no key. It returns the price, the official price and your discount for exactly the input you send.

curl -X POST https://cheapergen.com/api/v1/quote/bfl/flux-2-max/text-to-image \
  -H "Content-Type: application/json" \
  -d '{"prompt":"Editorial photo of a ceramic vase with dried flowers on a linen-covered table, soft north light, film grain","aspect_ratio":"1:1","resolution":"1MP"}'

API errors and what to do
Status	Code	Meaning
400	invalid_request	A parameter is missing or out of range — the message names it.
401	unauthorized	Missing, malformed or revoked API key.
402	insufficient_balance	Not enough credits for the quoted price; top up or enable auto top-up.
429	rate_limited	Too many requests or generations in progress; back off and retry.
502	upstream_error	The model provider failed; the hold is refunded and you can retry.
503	model_unavailable	No healthy route right now; retry later or pick another model.

Full FLUX.2 [max] API documentation

FAQ

FLUX.2 [max] API questions

No. The API is plain HTTPS with JSON, so the Python (requests) and Node.js (fetch) examples on this page are complete programs. Any language that can send an HTTP request works.

Yes. Add "webhook_url" to the request body and we POST the finished generation to it, signed with a CheaperGen-Signature header (HMAC-SHA256 of the timestamp and raw body). Polling GET /api/v1/generations/{id} works too.

Text to Image starts at $0.0616/image; the example request on this page costs $0.062, 12% below the official price. Failed generations are refunded automatically.