If you're looking for a service that supports popular Stable Diffusion models like Automatic1111 and Comfy, DiffusionHub is a good option. The service lets you run Stable Diffusion without a GPU, so it's a good option for those who don't have the hardware or don't want to bother. DiffusionHub supports a variety of models and is geared for people who want to concentrate on their creative work, not the plumbing.
Another option is RunDiffusion, a cloud-based service that offers preconfigured open-source AI tools like Automatic1111 WebUI, Comfy UI and others. RunDiffusion has a user-friendly interface that requires no programming knowledge, so it's good for both enthusiasts and pros. The service offers several pricing tiers, including a free trial and a premium subscription with extra features.
ThinkDiffusion is another option. It's a cloud-based service that supports several Stable Diffusion interfaces, including Fooocus and Automatic1111, and comes with 200 GB of persistent storage. ThinkDiffusion is geared for creatives, agencies and businesses, with a number of features and community resources to help people improve their images without worrying about the technicalities.
If you want a web interface, GRAVITI Diffus is a good option for creating and sharing AI-generated digital art. It's got features like ControlNet and One Click Face Swapper, and offers a free tier and several paid options, including an API tier for developers. The service has a lot of community resources and tutorials to help you get started with Stable Diffusion.