ComfyUI
Node-graph UI for Stable Diffusion / Flux / Hunyuan / Wan etc. — drag and connect boxes instead of writing prompts in a textbox.
By "comfyanonymous", 2023. Open source (GPL-3.0). Exposes every step of the diffusion pipeline (model, sampler, scheduler, VAE, ControlNet, LoRAs) as a node. Workflows can be exported as JSON and re-imported.
Beats AUTOMATIC1111 (classic Stable Diffusion WebUI) for pros who want full control. Loses for "type a prompt, get an image" where A1111 / Fooocus are simpler.