Black Forest Labs图像快速版

FLUX.2 [klein] 4B 文生图 API

Name: FLUX.2 [klein] 4B API
Brand: Black Forest Labs
SKU: bfl/flux-2-klein-4b
Availability: InStock

由 Black Forest Labs 提供文生图与 FLUX.2 [klein] 4B。速度最快的 FLUX.2——开放权重，低于一秒，价格不到一分钱的一小部分。

bfl/flux-2-klein-4b/text-to-image

起价最高 −93%

$0.001/img$0.014

每张图像 · 1K

使用 Max：起价 $0.0009/img →运行正常100% 正常运行时间（30 天）中位数 2s

用 FLUX.2 [klein] 4B 创作获取 API 密钥

API 文档 →对比模型 →

试用 FLUX.2 [klein] 4B 文生图

提示词*

0/5000

宽高比

输出图像比例。

分辨率

1K ≈ 1 MP；2K ≈ 4 MP（长边最高 2048 像素）。

Enable Safety Checker

Always on here. Set enable_safety_checker to false over the API to turn it off.

If set to true, the safety checker will be enabled. Content our Acceptable Use Policy prohibits stays blocked either way.

预计费用…

使用 Google 或电子邮箱免费创建账户，只为你生成的内容付费。

你的图像会显示在这里

输入提示词，选择设置，然后点击“运行”。仅成功生成的结果会收费。

还可查看：FLUX.2 [klein] 4B 图像编辑

查看 FLUX.2 [klein] 4B 示例和提示词

FLUX.2 [klein] 4B 文生图 API

POST/api/v1/run/bfl/flux-2-klein-4b/text-to-image

提交异步任务并返回 202 和生成任务 ID。请轮询 GET /api/v1/generations/{id} 或传入 webhook_url。参见任务生命周期。

输入参数

名称	类型	说明	影响价格
`prompt`必填	string	描述镜头，包括主体、动作、镜头运动、光线和风格。	否
`aspect_ratio`	string (enum)	输出图像比例。可选值：1:1 · 4:3 · 3:4 · 16:9 · 9:16 · 3:2 · 2:3 默认值：1:1	是
`resolution`	string (enum)	1K ≈ 1 MP；2K ≈ 4 MP（长边最高 2048 像素）。可选值：1K · 2K 默认值：1K	是
`seed`	integer	使用相同的 seed 和设置即可复现结果。留空则随机生成。	否
`enable_safety_checker`	boolean	If set to true, the safety checker will be enabled. Content our Acceptable Use Policy prohibits stays blocked either way. 默认值：true	否
`webhook_url`	string (URL)	可选。生成完成后，我们会在此地址 POST 结果，并使用你的 Webhook 密钥进行签名。Webhooks	否

请求

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-klein-4b/text-to-image`, {
  method: "POST",
  headers,
  body: JSON.stringify({
    "prompt": "舒适的咖啡馆室内，复古家具，清晨阳光，照片",
    "aspect_ratio": "1:1",
    "resolution": "1K"
  }),
}).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);

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-klein-4b/text-to-image", headers=headers, json={
    "prompt": "舒适的咖啡馆室内，复古家具，清晨阳光，照片",
    "aspect_ratio": "1:1",
    "resolution": "1K"
}).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"])

curl -X POST https://cheapergen.com/api/v1/run/bfl/flux-2-klein-4b/text-to-image \
  -H "Authorization: Bearer $CHEAPERGEN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
  "prompt": "舒适的咖啡馆室内，复古家具，清晨阳光，照片",
  "aspect_ratio": "1:1",
  "resolution": "1K"
}'

响应

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "bfl/flux-2-klein-4b",
  "endpoint": "bfl/flux-2-klein-4b/text-to-image",
  "mode": "text-to-image",
  "status": "queued",
  "input": {
    "prompt": "舒适的咖啡馆室内，复古家具，清晨阳光，照片",
    "aspect_ratio": "1:1",
    "resolution": "1K"
  },
  "output": null,
  "error": null,
  "cost": {
    "amount_usd": 0.2255,
    "currency": "usd",
    "estimated": true,
    "official_usd": null,
    "list_price_source": "official",
    "list_price_label": "Official",
    "saved_usd": null
  },
  "source": "api",
  "started_at": null,
  "completed_at": null,
  "urls": {
    "get": "https://cheapergen.com/api/v1/generations/gen_8c2QmX1nq0k4",
    "cancel": "https://cheapergen.com/api/v1/generations/gen_8c2QmX1nq0k4/cancel"
  },
  "created_at": "2026-10-15T09:21:04Z"
}

{
  "id": "gen_8c2QmX1nq0k4",
  "object": "generation",
  "model": "bfl/flux-2-klein-4b",
  "endpoint": "bfl/flux-2-klein-4b/text-to-image",
  "mode": "text-to-image",
  "status": "succeeded",
  "input": {
    "prompt": "舒适的咖啡馆室内，复古家具，清晨阳光，照片",
    "aspect_ratio": "1:1",
    "resolution": "1K"
  },
  "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,
    "list_price_source": "official",
    "list_price_label": "Official",
    "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"
}

FLUX.2 [klein] 4B 定价

按每张图像按量付费，无需订阅。生成失败会自动退款。

档位	官方价格	CheaperGen	可节省
1K 约 1 MP	~~$0.014~~/img	$0.001/img 订阅月度套餐后： Max $0.0009	−93%
2K 约 4 MP	~~$0.0172~~/img	$0.0038/img 订阅月度套餐后： Pro $0.0037Max $0.0036	−78%