FLUX.1 dev

FLUX.1 dev is the open-weight tier of Black Forest Labs’ FLUX image generation family, released in August 2024 alongside the closed FLUX.1 Pro. Black Forest Labs was founded by former Stability AI researchers, including some of the people behind the original Stable Diffusion, and FLUX uses a 12 billion parameter rectified flow transformer architecture rather than the U-Net diffusion designs common in earlier text-to-image models. Dev is a guidance-distilled version of the full Pro model, which makes it faster to run while keeping most of the image quality and prompt adherence of its closed sibling. Black Forest Labs licenses it for non-commercial use only, distributing the weights on Hugging Face, while companies that want to use it commercially need to buy a separate license through BFL. It quickly became one of the most widely fine-tuned and remixed open image models after release, with strong adoption on platforms like Replicate and in the Stable Diffusion community’s tooling such as ComfyUI.