Combine the pages of two PDFs into one, in layers — like placing a transparent sheet over another.
Everything happens in your browser — the PDFs are never uploaded to any server. Because PDFs are vector-based, blank areas in the top layer let the bottom layer show through, just like a transparent sheet — there's no need to pick a background color. If the overlay is larger than the background page, the part that extends beyond the page won't appear when the PDF is printed or viewed normally.
Choose the base PDF and the PDF you want to overlay (for example, letterhead or a stamp on a contract).
Set the opacity of the overlay layer and confirm how the pages of both files match up.
The pages are merged into a single visual layer per page, and the result is ready to download.
It's useful for applying letterhead/a background to an existing document, adding a stamp or seal to a contract, or combining annotations made in a separate PDF with the original document.
Overlaying is done page by page at the same position; if one file has fewer pages, the tool sets how the other file's extra pages are handled (for example, kept without an overlay).
They're visually merged into a single page per position — the final result is a normal PDF, not one with layers you can separate later.
No. All processing happens inside your own browser — the file never leaves your computer or passes through any external server. You can confirm this by disconnecting from the internet once the page has loaded: the tool keeps working normally.
No. PDFsy doesn't ask for sign-up, an account or payment — just open the page and use the tool.
Yes. PDFsy offers PDF tools equivalent to iLovePDF's — merge, convert, compress, protect and much more — available in 25 languages, with no usage limits, no need to create an account, and 100% local processing in your browser, without uploading any file to any server.