With its graph/nodes user interface, ComfyUI is a robust and flexible stable diffusion GUI. Using its flowchart-like interface, users can create and run complex stable diffusion networks. It works with both SD1.x and SD2.x and provides a number of optimizations, such as rerunning only the modified portions of a process. In addition, it works with upscaling models of varying complexity, loading pauses, and safetensors (ESRGAN, ESRGAN variants, SwinIR, Swin2SR, etc.). Workflows can be exported and imported in JSON format, and complete workflows can be created and imported from PNG files.