What happens to your pictures
When you select images, the browser creates a local reference to each file and decodes it in memory. Nothing is posted anywhere: the page has no upload endpoint and no account system, and the recorder captures the canvas directly instead of a file that travelled across the network. Close or refresh the tab and the temporary project is gone.
Wide photos and tall photos
The canvas is landscape, so the tool fits each picture inside the frame rather than cropping it. A wide photo fills the 16:9 frame; a tall portrait is centred over a dark background instead of being stretched. The preview shows exactly the framing the export will use, so you can check the composition before you record.
Converting a single picture or a whole set
Drop in one photo and you get a short clip of it. Drop in an album and the tool records them in the order you arranged, each for its own duration between 1 and 30 seconds. The page does not impose a photo maximum; what limits you is your device's memory and the size of the files, so a large batch is worth testing in a smaller run first.
The file you end up with
A 1280 × 720 clip at 30 frames per second, saved as photo-slideshow.webm in Chrome and Edge, or as MP4 in browsers that can record it. There is no watermark on the frames and no fee to remove one, because none is added in the first place.
Related pages
Start from create video from photos if you want the step-by-step version of the same workflow, or from video with pictures and music if you are adding a soundtrack.