How it works
Private by design. We cannot see your photos because they are never uploaded. Turn on airplane mode and it still works.
What actually happens
When you choose photos, the browser hands this page a reference to the files on your own disk. The page reads them, decodes them into memory, arranges them and draws the result onto a canvas. When you download, the finished image is assembled in the same tab and written straight to your device. At no point is a photo sent anywhere, because there is nowhere for it to be sent: this site has no server that accepts images.
How you can check
Load the page once, then turn on airplane mode or disconnect from the network, and make a collage anyway. It works, because nothing it does needs a connection. If you would rather watch than trust, open your browser's developer tools, go to the network tab, and make a collage — you will see the page's own files load and nothing leave afterwards.
What is stored, and where
Your projects are saved in your browser's own storage on this device, so you can close the tab and come back. That storage is yours: clearing your browser data removes it, and it is never synchronised anywhere. If you want a copy on another device, export a project file and move it yourself.
What the exported file contains
The collage and nothing else. No watermark, and no metadata: the output carries no EXIF, no GPS coordinates, no camera model and no capture time, because it is built from pixels rather than copied from your originals. Capture times are read while you work, for ordering photos by date, and are never written out. Location data is never read at all.
What we can see
Which pages were visited and whether an export succeeded, in aggregate and without anything identifying. We cannot see your photos, how many you used, or what they are of, and there is no account to attach anything to in the first place.