LocalSlideshow is a single html static file that allows you to specify a local folder and it display a slideshow of the pictures in this folder and any sub-folder. Nothing is uploaded to any server. Everything is kept locally in your browser. This works offline if you save the page first.
There's not many bells or whisles. This was just a little experiment to build the most lightweight tool for this without using external dependencies.
Pull requests to improve or add functionalities are welcome.
One of the main missing thing is a loading indicator while the browser reads the folders. I tested with 21k files in 200+ sub-folders. It works but takes a good few minutes to reach loading the first image.
This tool is part of the F² MicroTools suite. A collection of tools that that are tiny, with no dependencies and typically just do one thing.