AI Image Enlarger is a website which lets you upscale images up to 2x for free. For higher resolution upscaling you’ll need to purchase a plan. In addition to upscaling, it also offers tools to enhance and adjust colors and light balance, deblur and sharpen images, retouch and fix blurry faces, remove backgrounds and more. You need to register an account and log in to use the tool and you only get 8 credits on the free plan, it can still be handy if you’re looking for a quick, free upscale.
