FLUX.2 Klein 4B

Black Forest Labs chatvisionimage_gentool_use Free

API ID: black-forest-labs/flux.2-klein-4b

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Input Price
Free
/1M tokens
Output Price
Free
/1M tokens

About FLUX.2 Klein 4B

FLUX.2 [klein] 4B is the fastest and most cost-effective model in the FLUX.2 family, optimized for high-throughput use cases while maintaining excellent image quality. Pricing is based on the output image. The first generated megapixel is charged $0.014. Each subsequent megapixel is charged $0.001.

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Price Ranking
#6 lowest price among 1240 Chat models — Top 20% cheapest!

Model Specifications

Context Length
41k
Max Output
—
Release Date
2026-01-14
Capabilities
chat vision image_gen tool_use
Input Modalities
textimage
Output Modalities
image

Best For

  • Image analysis, document understanding, visual Q&A
  • Conversations, content writing, general assistance
🎉

This model is completely free!

No token costs - use it without worrying about API bills.

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Black Forest Labs Model Lineup

Compare all models from Black Forest Labs to find the best fit

Model Input Output Context Capabilities
FLUX.2 Klein 4B Current Free Free 41k chat vision image_gen tool_use
FLUX.2 Max Free Free 47k chat vision image_gen
FLUX.2 Flex Free Free 67k chat vision image_gen
FLUX.2 Pro Free Free 47k chat vision image_gen
View All Black Forest Labs Models →

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🚀 Quick Start

Get started with FLUX.2 Klein 4B API

OpenAI-compatible SDK 
from openai import OpenAI

client = OpenAI(
    base_url="https://api.provider.com/v1",
    api_key="YOUR_API_KEY"
)

response = client.chat.completions.create(
    model="black-forest-labs/flux.2-klein-4b",
    messages=[
        {"role": "user", "content": "Hello!"}
    ]
)
print(response.choices[0].message.content)

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