FLUX.2 Klein is an open-source AI image generation model from Black Forest Labs that produces high-quality images in under one second, available in 4B and 9B parameter variants with a commercial-friendly Apache 2.0 license.
What is FLUX.2 Klein?
FLUX.2 Klein is a distilled rectified flow transformer for text-to-image generation, image editing, and image combination. It accepts text prompts and optional input images (single or multiple) and outputs images up to 1024×1024 resolution (4B model) or higher, using only 4 inference steps. It runs on consumer GPUs and is developed by Black Forest Labs, the team behind the original FLUX models.
Key Features
- Sub-Second Generation — Generates 1024×1024 images in ~0.5 seconds on GB200 hardware or ~2 seconds on an RTX 5090, while maintaining output quality that matches models 5× its size.
- Two Model Sizes — The 4B model (Apache 2.0 license) is optimized for consumer GPUs; the 9B model offers maximum quality with FP8 quantized versions available.
- 4-Step Inference — Step-distilled from a larger base model to just 4 inference steps without sacrificing image fidelity, enabling real-time workflows.
- Multi-Reference Editing — Edit images using up to three reference inputs in a single workflow (e.g., combine a person from one photo with a cat from another).
- Qwen3 Text Encoder — An 8B parameter text embedder provides superior prompt understanding and adherence.
- C2PA Watermarking — Built-in content provenance with cryptographically signed metadata for responsible use.
- Seamless Integration — Works with Hugging Face Diffusers, ComfyUI, NVIDIA TensorRT, and the Black Forest Labs API for production deployment.
Who is it for?
- AI researchers and developers — Evaluate and fine-tune the 4B or 9B model using the base weights and custom pipeline access, with full commercial license under Apache 2.0.
- Creative professionals — Generate marketing visuals, product mockups, or infographics in under a second, with the ability to edit images via text instructions.
- Hobbyists and indie creators — Run the 4B model on consumer GPUs (e.g., RTX 5090) with the free Starter plan, producing 50 images per day.
What can you do with FLUX.2 Klein?
- Text-to-image generation — Create photorealistic scenes, stickers, or infographics from detailed prompts like “Soaking wet capybara taking shelter under a banana leaf.”
- Multi-image editing — Combine elements from multiple photos into one coherent image, e.g., place a person from image 1 petting a cat from image 2.
- Style transfer and variant creation — Generate variations of an input image (e.g., change the color of a vase on a table) while preserving composition.
Pricing
Freemium model. Starter (free): 50 images per day, 4B model only, 1024×1024 resolution. Creator ($9.9/month): 1,000 images per month, both 4B and 9B models, up to 2048×2048 resolution, API access. Enterprise ($199/month): unlimited generations, all model variants, maximum resolution, dedicated endpoints, priority support, and SLA guarantee.
FAQ
What’s the difference between the 4B and 9B models?
The 4B model has 4 billion parameters, uses an Apache 2.0 license, and runs efficiently on consumer GPUs. The 9B model has 9 billion parameters and matches the quality of models 5× its size, offering maximum fidelity but requiring more VRAM.
What GPU do I need to run FLUX.2 Klein locally?
The 4B model can run on consumer GPUs like the RTX 5090, generating images in ~2 seconds. The 9B model benefits from more VRAM; FP8 quantized versions help reduce memory requirements.
Can I use FLUX.2 Klein for commercial projects?
Yes, the 4B model is released under Apache 2.0 license, which permits commercial use. The 9B model also supports commercial licensing through the Black Forest Labs API or direct license.
