FreeScaler 4+

It's open source. It's totally free. It's local on my computer and not a separate website or service. It upscales batches of any amount. It has great upscale outputs. It's totally free. And it's also free. I can't believe more people aren't using this.

There are definitely some things I would change about the app, but it's still better than the alternaties. But for instance, give us a "are you sure?" window when hitting "clear". I've messed up multiple times after doing a batch that took hours. Also, allow the "save as" to work for all items finished in a batch that has been stopped early. I had to stop a large batch early one time that had hundreds of finished upscales. So then I had to individually save each one that was finished. Took forever, but better than starting over.

All I can say is "WOW! And it's free." I was looking for an app that could effectively upscale isolated AI-generated images to prepare them to upload to stock photo sites. I have tried multiple online upscalers and I have image editing software on my Mac that I use for the task, but all of those options have been lacking batch upscaling - which I found very useful and effective in FreeScaler. I also like how simple the interface is, and I appreciate the pop-up tips. It's easy to switch AI upscale modes (Anime mode seems to work the best for me with AI-generated illustrations) and adding TTA mode has been helpful too. I'm thrilled with how well this works and how easy it is to use. Don't wonder if it's worth it - just get it - it works.

I'm not afraid of the command line, so I'm already familiar with the open source tools behind this app. However I purchased Topaz Gigapixel AI for the convenient GUI. This app may not have as many sliders and options as Gigapixel, but for my hobbyist use cases I could easily see myself foregoing future Topaz upgrades. Kudos to this and other developers for making easy-to-use GUI frontends for complex and esoteric software.