FreeU is a research method from S-Lab at Nanyang Technological University published at CVPR 2024 Oral. It improves diffusion model outputs without additional training or fine-tuning by modulating skip connections and backbone features in the U-Net. The technique can be integrated into existing diffusion models including Stable Diffusion to boost generation quality at no computational cost, making it applicable to both text-to-image and image-to-image generation pipelines.