Overlay & Background PDF Tool
Overlay one PDF onto another similar to a watermark background.
How to overlay two PDFs — 3 steps
- 1
Add both documents
Provide the base document and the one to lay over it. Both are processed in your browser, so neither is uploaded.
- 2
Set which goes on top
Decide the order. The overlay is drawn over the base, so anything opaque in it will conceal what sits underneath at that position.
- 3
Download the combined file
The pages are merged into a single document in which both sets of content occupy the same pages.
Overlaying is not merging
The two operations sound similar and do opposite things. Merging is sequential: two ten-page documents become one twenty-page document, with the second following the first. Overlaying is simultaneous: two ten-page documents become one ten-page document in which each page carries the content of both, drawn on top of each other.
The distinction decides which tool you want. If you are assembling a report from separate sections, or attaching appendices to a submission, you want to merge. If you want content from one document to appear on the pages of another — a background, a frame, a stamp, a set of markings — you want to overlay.
Because both sets of content are drawn onto the same page, the result stays fully a PDF rather than becoming an image. Text from either document remains selectable and searchable, vector graphics stay sharp at any zoom, and nothing is flattened or re-rendered in the process.
Where an overlay is the right instrument
The classic use is applying pre-printed stationery to generated content. Invoices, statements, and letters produced by a business system usually come out as plain content on a blank page, and overlaying a letterhead PDF puts the company's logo, footer, and design onto every page in one operation — without modifying the system that generates them. The same approach applies certificates borders, form backgrounds, and branded frames to output that was never designed to carry them.
Stamping is the other common case: applying a DRAFT, CONFIDENTIAL, or APPROVED mark, a company seal, a page border, or a set of registration marks across a document. Where the overlay has a transparent background it sits over the content cleanly; where it is opaque it will hide what is beneath, which is occasionally the intention and more often an unwelcome surprise.
Two practical points govern whether the result looks right. The pages need to be the same size and orientation — overlaying an A4 file onto a Letter document leaves the two misaligned, and one will be offset or clipped relative to the other. And the page counts need thinking about: if the documents differ in length, decide whether the shorter overlay should repeat across every page, which is what you want for a letterhead, or apply only to the pages it has, which is what you want when marking specific pages. Check the finished file page by page rather than only looking at the first one.
Your files never leave your device
Both documents are combined in your browser, so business correspondence, statements, and branded templates are processed entirely on your own machine.
Most online PDF sites upload your document to their servers, process it there, and keep a copy for minutes, hours, or longer. PilotPDF works differently: the page downloads a small processing engine into your browser, and your file is opened and edited in your device's memory using WebAssembly. Nothing is transmitted, so there is nothing for a server to store, leak, or scan. You can even disconnect from the internet after the page loads and the tool keeps working.
Read more about how this works in our privacy-by-design explainer.