Removes a single common top-level folder from a .zip archive, so its contents sit at the root of a new zip instead of one level deeper.
Common with GitHub downloads and some export tools that wrap everything in one named folder — flattening makes the archive easier to extract in place.
Drop a .zip file. If every entry shares one top-level folder, a button appears to flatten and download a new zip.
Only works when there's a single common top-level folder shared by every entry. Archives with multiple top-level items have nothing to flatten.