Forty photos of a building site or a property inventory: nobody opens them one by one. On a single sheet, everybody looks at them. Drop them in, choose the number of columns, save.
What it does not do: The sheet is an IMAGE, not a PDF: it prints and attaches, but its text cannot be searched. The thumbnails are reduced: it is an index, not a print. To look at a photo in detail you need the original. And nothing is sorted: the order is the order you dropped them in, because guessing at a “logical” order would be guessing.
Nothing is uploaded. Cut your network connection once this page has loaded: the tool keeps working. How to check it yourself.