PDF Overlay – Overlay One PDF on Top of Another
A free PDF overlay tool that lets you overlay 2 PDFs, overlap their pages, or layer one PDF on top of another. Control opacity, position and page alignment — useful for letterheads, stamps, watermarks, signatures and comparing revisions. Everything runs in your browser, so your files are never uploaded. No signup, no watermark, no page limits.
Upload & Configure
Drag & Drop your Base PDF here
or
Drag & Drop your Overlay PDF here
or
Preview & Download
Upload PDF files to see preview
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How to Overlay PDFs in 3 Steps
New to this? Read our full guide on how to overlay a PDF — superimpose, layer & stack documents, with 7 practical use cases.
1. Select Your PDFs
Upload your base PDF and the overlay PDF. The files are processed securely in your browser, never uploaded to any server.
2. Customize Settings
Adjust the overlay opacity, position, and page alignment to get the perfect combination of your documents.
3. Process & Download
Click "Process Overlay" and download your combined PDF. Your new document will be generated instantly for you to download.
Your Security is Our Priority
100% Private & Secure
Your PDFs are processed entirely in your browser. No files are ever uploaded to a server, guaranteeing your data's privacy.
Instant, Browser-Based
Because there are no uploads, the overlay process is instant. Your combined PDF is ready as soon as you click the button.
Completely Free
Overlay unlimited PDF files for free. No watermarks, no limits, and no registration required.
Overlay, Overlap, Layer, Superimpose — All the Same Job
People describe this task in at least five different ways, and the wording trips up more searches than the task itself. If you are trying to overlap two PDF pages, layer PDFs on top of each other, superimpose one document over another, or simply overlay 2 PDFs, you want the same operation and this is it.
There is one distinction that genuinely matters, and it is not about vocabulary:
| You want | The right operation |
|---|---|
| Both documents visible on the same page | Overlay — this tool |
| One document after the other, in sequence | Merge |
| Repeating text across pages, no source file | Watermark |
Reaching for merge when you meant overlay is the single most common mistake here — you end up with a letterhead on page 1 and your document starting on page 2, rather than the letterhead sitting behind every page.
Overlaying two PDFs of different lengths
The Page Alignment setting decides what happens when the two files do not have matching page counts. Match Pages pairs them one-to-one and stops when the shorter file runs out. Overlay First Page on All takes a single overlay page and repeats it across every page of the base document — the setting you want for a letterhead or a company template. Single Overlay on First Page Only stamps just the cover.
Overlapping scanned pages to compare them
Setting opacity to roughly 50% and using Match Pages turns the overlay into a difference check: two revisions of a drawing, a form, or a contract laid directly over one another, so anything that moved stands out immediately. It is a quick visual diff that needs no special software. For a structured side‑by‑side instead, use Compare PDFs.
Why the overlay file needs the same page size
Overlay positions content by coordinates, not by scaling to fit. An A4 overlay dropped onto a US Letter base will sit slightly off, and a small stamp saved on a small page will land in a corner rather than where you drew it. Export the overlay at the same page dimensions as the base document and the placement becomes exact.
Frequently Asked Questions
Is it safe to overlay confidential PDFs with this tool?
Yes. This tool is 100% secure. All processing happens locally in your web browser. Your PDF files are never uploaded to any server, so your sensitive information remains completely private.
What's the difference between PDF overlay and PDF merging?
PDF merging combines pages from different documents sequentially, while PDF overlay places one PDF on top of another, creating a layered effect. Overlay is perfect for adding watermarks, signatures, or annotations to existing documents.
Can I overlay multiple pages from the overlay PDF?
Yes. You can choose to match pages (page 1 overlays page 1, page 2 overlays page 2, etc.), overlay the first page on all pages, or overlay only on the first page of the base document.
How do I overlap two PDF pages on top of each other?
Load the document you want underneath as the base file and the one you want on top as the overlay, then set the opacity and position. Overlapping and overlaying are the same operation — both files end up sharing a page rather than following one another.
Can I overlay 2 PDFs with different numbers of pages?
Yes. Use Overlay First Page on All to repeat a single overlay page across every page of the base document, which is what a letterhead or template needs. Match Pages pairs them one to one and stops when the shorter file runs out.
Why is my overlay landing in the wrong place?
Almost always a page-size mismatch. Overlay places content by coordinates rather than scaling to fit, so an A4 overlay on a US Letter base sits slightly off. Export both files at the same page dimensions and placement becomes exact.
What file size limitations are there?
There are no specific file size limitations, but very large PDFs may take longer to process depending on your device's capabilities. For best performance, we recommend files under 100MB.
What is a PDF overlay?
A PDF overlay places the contents of one PDF directly on top of another, creating a single layered document. Unlike merging (which puts pages one after another), an overlay superimposes pages so both appear together — ideal for adding a letterhead, stamp, watermark, or signature over an existing document.
How do I overlay two PDFs on top of each other?
Upload your base PDF and the overlay PDF, set the opacity, position and page alignment, then click "Process Overlay" and download the result. The two PDFs are layered on top of each other entirely in your browser — nothing is uploaded.
Can I superimpose or layer one PDF over another?
Yes. This is exactly what the tool does — it superimposes (layers) one PDF over another. You control the transparency with the opacity slider, so you can stack documents with a faint, see-through overlay or a fully opaque one.
Can I overlay a watermark, stamp, or image-based PDF?
Yes. Any PDF can be used as the overlay layer, including a logo, letterhead, stamp, signature, or an image saved as a PDF. Lower the opacity for a watermark-style effect, or keep it at 100% to place a solid stamp on the page.
What People Usually Do Before and After an Overlay
Overlaying is rarely the whole job. These are the steps that most often sit either side of it, in the order they normally come up.
Before overlaying
If the two files have a different number of pages, or the pages are out of order, fix that first — an overlay maps page 1 onto page 1, page 2 onto page 2, and so on. Use rearrange PDF pages to reorder, remove PDF pages to drop blanks, or extract PDF pages to pull out just the range you want to stamp. To put several documents behind a single letterhead, merge the PDFs into one file first.
After overlaying
A stamped or letterheaded document usually needs finishing. Add page numbers to the PDF so the combined document paginates correctly — useful when the overlay produced a single set from several sources. Add a watermark if the file needs a DRAFT or CONFIDENTIAL marker on top of the overlay, compress the PDF when the layered result is larger than you want to email, and password-protect the PDF before sending it on.
Related reading
Branding a document? Adding a letterhead, stamp or template to a PDF covers the exact settings for applying one design across every page. For a general walkthrough, see how to overlay a PDF. If you are weighing this against a desktop tool, why files never leave your browser explains how the in-browser processing works.