If you want a platform to make your own pixel art style, Pixelfy is a great option. This AI tool lets you generate pixel art in a variety of styles, including backgrounds, fantasy RPG characters and 16x16 pixel portraits. Pixelfy has advanced features like a prompt builder, grid size control, sampling step control, prompt guidance, background removal and color palette control. It's open-source, too, so developers and creative pros can get involved.
Another option is OpenArt, which converts text-to-image prompts into pixel art. It's got a range of AI drawing tools and editing options so artists can create their own styles and models. OpenArt's higher-end features include boundary-free AI drawing, object removal and the ability to train your own model. It's got a range of pricing options depending on how much art you want to make.
Last, Makeayo has a friendly interface and powerful AI abilities. It's got unlimited generations, HD upscaling to 4k resolution and pose matching for more dynamic artistic results. It works on Windows, Mac and Linux, too, so Makeayo is a good option if you want to experiment with generative art.