Yes, that's exactly right. All your images are processed locally and don't leave your device. They are all processed in the web browser with javascript and your dev tools like you say should show that.
I think he means "why does it have to upload to the browser, can't it just read from the filesystem?" it should work, but browsers make it more complicated.
Thanks for sharing! Both the link and the story. As a University student and someone that has here also made a photomosaic app, that is super relatable.
That's good to know about the pricing. It's free for now. Honestly didn't expect this level of interest (there's 307 people on the site right now according to analytics).
With that interest, I may add some plans - potentially for the commercial use in particular
But, please, give us some nitty gritty of how you made it