Overlay two PDFs

Overlaying two PDFs lays the pages of a second document on top of those of a first, like a transparent layer: letterhead on a letter exported without a layout, a graphic frame or template, a title block on a plan, legal notices in the footer, a logo repeated on every page. The layer stays vector-based and sharp, and the composition is done in your browser.

Select two files: the first is the base document, the second the layer. Each layer page is scaled proportionally to fit the base page, centred, then drawn on top of its content at the chosen opacity, from 5 to 100% (100% by default).

With the repeat option checked, the layer pages are reused in a loop: a one-page layer applies to every page of the document, a two-page layer alternates between odd and even pages. Unchecked, layer page 1 goes on document page 1, page 2 on page 2, and the remaining pages are left untouched.

Because the layer sits on top, its filled areas hide whatever is underneath. A letterhead therefore needs a transparent background, which is the case for most PDFs exported from layout software; a scanned letterhead with its white background would cover the text unless you lower the opacity.