FLUX.1-dev is a refined flow transformer with 1.2 billion parameters capable of generating images from text descriptions. It represents the latest advancements in text-to-image generation technology, delivering superior output quality, second only to its professional model, FLUX.1 [pro]. The model enhances efficiency through guided distillation training and offers open weights to facilitate novel scientific research, empowering artists to develop innovative workflows. The generated outputs can be utilized for personal, scientific, and commercial purposes, as specified in the flux-1-dev-non-commercial-license.