FLUX.3 Klein

image

Generates images from text prompts with FLUX.3 Klein, with configurable image size, reproducible seeds, prompt expansion and optional bounding-box layout control.

MODALITIES

image

FLUX.3 Klein (blackforestlabs/flux-3/klein/text-to-image) is a image model from Blackforestlabs. Pricing via AIgateway: $0.0090 per megapixel. Call it via https://api.aigateway.sh/v1/images/generations — set model="blackforestlabs/flux-3/klein/text-to-image".

model · blackforestlabs/flux-3/klein/text-to-image

Use this model

model: blackforestlabs/flux-3/klein/text-to-image

curl https://api.aigateway.sh/v1/images/generations \
  -H "Authorization: Bearer $AIGATEWAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"blackforestlabs/flux-3/klein/text-to-image","prompt":"a serene cyberpunk city at dusk"}'

curl https://api.aigateway.sh/v1/images/generations \ -H "Authorization: Bearer $AIGATEWAY_API_KEY" \ -H "Content-Type: application/json" \ -d '{"model":"blackforestlabs/flux-3/klein/text-to-image","prompt":"a cyberpunk cat"}'

Capabilities

Text to image

Pricing

Per megapixel$0.0090

You pay pass-through pricing.

See API example →Compare API reference See usage ranking →

Collections

More image models →More from Blackforestlabs →Frontier models →Free-tier models →

API schema

Call FLUX.3 Klein from any OpenAI SDK

POST https://api.aigateway.sh/v1/images/generations·Content-Type: application/json·Auth: Bearer sk-aig-...

Request body

json

{
  "model": "blackforestlabs/flux-3/klein/text-to-image",
  "prompt": "A cyberpunk cat at sunset, cinematic lighting",
  "n": 1,
  "size": "1024x1024",
  "response_format": "url"   // or "b64_json"
}

Response

json

{
  "created": 1776947082,
  "data": [
    { "url": "https://media.aigateway.sh/img/abc123.png" }
    // or { "b64_json": "iVBORw0KGgoAAAANSUhEU..." }
  ]
}

Quickstart

from openai import OpenAI
client = OpenAI(base_url="https://api.aigateway.sh/v1", api_key="sk-aig-...")

r = client.images.generate(
    model="blackforestlabs/flux-3/klein/text-to-image",
    prompt="a cyberpunk cat at sunset",
    size="1024x1024",
)
print(r.data[0].url)

Errors

401authentication_errorInvalid or missing API key

402insufficient_creditsWallet empty (PAYG only)

404not_foundUnknown model or endpoint

429rate_limit_errorOver per-minute limit — see Retry-After header

500server_errorUpstream provider failed (retryable)

503service_unavailableUpstream saturated (retryable)

Full docs →API reference →OpenAPI spec →llms.txt →

Frequently asked questions

What is FLUX.3 Klein?

Generates images from text prompts with FLUX.3 Klein, with configurable image size, reproducible seeds, prompt expansion and optional bounding-box layout control. It is a image model from Blackforestlabs, accessible via AIgateway's OpenAI-compatible API at slug blackforestlabs/flux-3/klein/text-to-image.

How much does FLUX.3 Klein cost via AIgateway?

Pass-through pricing. See the pricing panel on this page for exact rates.

How do I call FLUX.3 Klein from my code?

Point the OpenAI SDK at https://api.aigateway.sh/v1 with your AIgateway key and set model to "blackforestlabs/flux-3/klein/text-to-image". The request and response shapes match OpenAI exactly.

Does FLUX.3 Klein support streaming, tool calling, vision, and JSON mode?

Streaming — no. Tool calling — no. Vision — no. JSON mode — no. Prompt caching — no.

Can I bring my own Blackforestlabs API key (BYOK)?

Yes. Attach a Blackforestlabs key in your AIgateway dashboard and this model flips to pass-through — you pay Blackforestlabs directly and AIgateway adds no platform fee on those calls.