The only free, high-limit AI upscaler that doesn’t insult you with watermarks, nag screens, or signup walls. - Free API (pypi.org/project/image-upscaling-api) - Large image support up to 4096*4096 - Supports transparent images

This website can upscale your images by 4x using AI. And the best part: it is completely free & no sign-up required! It supports images up to 5000x5000px to be scaled up to 20k — a size where most services charge a ton of money for!