questions/How-to

How do I use Flux-2-Klein-9b?

To use Flux-2-Klein-9b, install the OpenAI SDK (any language), point base_url at https://api.aigateway.sh/v1 with an sk-aig-... key, and set model="black-forest-labs/flux-2-klein-9b". That's it — no provider account, no separate billing. Black Forest Labs's model is served through AIgateway's OpenAI-compatible endpoint so every existing OpenAI integration (Cursor, LangChain, Vercel AI SDK) works unchanged.

How it works

1. Grab an AIgateway key

Sign in at aigateway.sh with GitHub or Google, open the dashboard, and copy an sk-aig-... key. No credit card required to claim a key — the free tier is 100 requests/day on Kimi K2.6 so you can test end-to-end before you upgrade.

2. Point the OpenAI SDK at AIgateway

Every OpenAI client library ships with a base_url (Python) or baseURL (Node) field. Set it to https://api.aigateway.sh/v1 and drop in your sk-aig-... key. Nothing else in your application code needs to change — the request and response schemas are OpenAI-identical.

3. Set model="black-forest-labs/flux-2-klein-9b"

On your chat.completions.create call (or images, embeddings, audio — whichever endpoint matches the image modality), pass model="black-forest-labs/flux-2-klein-9b". AIgateway handles provider auth, billing, retries, and transformation so Black Forest Labs-specific quirks don't leak into your code.

Code example

Python
# pip install aigateway-py openai
# aigateway-py: sub-accounts, evals, replays, jobs, webhook verify.
# openai SDK: chat/embeddings/images/audio — drop-in compat per our SDK's own guidance.
from openai import OpenAI

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

img = client.images.generate(
    model="black-forest-labs/flux-2-klein-9b",
    prompt="A studio photo of a red ceramic mug on white marble",
    size="1024x1024",
)
print(img.data[0].url)
Node / TypeScript
// npm i aigateway-js openai
// aigateway-js: sub-accounts, evals, replays, jobs, webhook verify.
// openai SDK: chat/embeddings/images/audio — drop-in compat.
import OpenAI from "openai";

const client = new OpenAI({
  baseURL: "https://api.aigateway.sh/v1",
  apiKey: process.env.AIGATEWAY_KEY,
});

const img = await client.images.generate({
  model: "black-forest-labs/flux-2-klein-9b",
  prompt: "A studio photo of a red ceramic mug on white marble",
  size: "1024x1024",
});
console.log(img.data[0].url);

Related

FAQ

Do I need a Black Forest Labs account to use Flux-2-Klein-9b?

No. AIgateway provides a unified sk-aig-... key that routes to Black Forest Labs on your behalf. You only need an AIgateway account.

Does Flux-2-Klein-9b support tool calling?

Flux-2-Klein-9b does not support tool calling natively. Use it for generation; route tool-calling prompts to a model like Claude Sonnet 4.6 or GPT-5.4.

What is the context window of Flux-2-Klein-9b?

Context window details for Flux-2-Klein-9b are on the spec page at /models/black-forest-labs/flux-2-klein-9b.

Is Flux-2-Klein-9b free to try?

AIgateway's free tier gives 100 requests/day on Kimi K2.6. Other models (including Flux-2-Klein-9b if it isn't Kimi K2.6) require a $5 top-up, then pass-through pricing.

Can I use Flux-2-Klein-9b with Cursor or LangChain?

Yes — anything that speaks OpenAI's API shape works. Set base_url to https://api.aigateway.sh/v1, paste your AIgateway key, and set the model string. Cursor, Cline, Continue, LangChain, LlamaIndex, Vercel AI SDK all supported.

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