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Lizely

PDF Overlay

Place pages from one local PDF over another with proportional centering and adjustable opacity, while preserving the base page count.

Privacy: your files never leave your device. All processing happens locally in your browser.

How to use

  1. 1.Choose a base PDF and an overlay PDF, each no larger than 25 MiB.
  2. 2.Set overlay opacity from 0.1 to 1 and review the documented single-page or multi-page mapping rule.
  3. 3.Create and download the overlaid PDF, then inspect every important page before distribution or print.

About PDF Overlay

PDF Overlay places pages from one local PDF on top of pages in another. Choose a base PDF, choose an overlay PDF, set opacity from 0.1 to 1, and select Overlay PDFs. The browser embeds overlay pages into the base document, proportionally fits each applied layer inside the corresponding base page, centers it, and serializes a new copy. Neither input nor the generated output is uploaded to Lizely.

The base PDF controls the output page count, page order, page boxes, and underlying content. Overlay content is drawn afterward, so it appears above the existing base-page artwork where it is opaque. The original base and overlay files are never overwritten. The download uses the base filename with -overlay added before the PDF extension.

Page mapping follows two explicit rules. If the overlay PDF has exactly one page, that page is repeated on every base page. This supports letterhead, border, stamp-sheet, and reusable foreground-layer workflows. If the overlay PDF has more than one page, overlay page 1 maps to base page 1, page 2 maps to page 2, and so on. Base pages beyond the overlay count remain unchanged, while overlay pages beyond the base count are ignored.

Each applied overlay page is scaled uniformly to fit inside the base page without cropping or stretching. Its aspect ratio is preserved, and the fitted result is centered horizontally and vertically. When the two page shapes differ, blank space can remain on two sides. The tool does not offer fill-and-crop behavior, arbitrary offsets, rotation controls, alignment corners, or separate scaling for width and height.

Opacity controls the drawing operation for the embedded overlay layer. A value of 1 applies the layer at full opacity; smaller accepted values make the layer more transparent where the PDF graphics model supports it. Existing transparency inside the overlay page remains part of that embedded artwork. The tool does not inspect blend modes, knockouts, overprint settings, spot colors, or printing separations, so print-critical files require professional preflight.

Overlay pages are embedded as PDF artwork instead of screenshots. Vector content and text can therefore remain vector-based to the extent supported by the existing library. Interactive elements such as links, comments, form fields, scripts, attachments, and outline destinations are not copied as equivalent interactive objects by this drawing operation. The output is a visual page overlay, not a semantic merge of every document structure.

Both inputs must be non-empty PDFs no larger than 25 MiB each. Encrypted, damaged, unsupported, oversized, and incorrectly labeled files produce a visible error, and password protection is not bypassed. A stale job cannot replace results made from newer file choices or opacity settings. Changing either input or opacity revokes the previous object URL and removes the obsolete download.

Users should inspect the result because a full-page opaque overlay can hide the base visually, and a dark layer can reduce readability even at partial opacity. Hiding content visually does not delete it from the base content stream and is not secure redaction. Similarly, placing a signature-looking image does not create a cryptographic digital signature or establish signer identity.

Use PDF Overlay for visual combinations such as placing letterhead above generated pages, adding a prepared border, combining a transparent design layer with a report, or pairing corresponding foreground sheets. Use Merge PDF to concatenate documents, Alternate Mix PDF to interleave pages, Add Watermark to PDF for generated text marks, and Sign PDF for a drawn signature workflow. This tool does not concatenate, reorder, redact, certify, or flatten the base document.

Methodology & sources

Validate two bounded PDFs and opacity, load both without bypassing encryption, retain the base document as the output structure, repeat a single overlay page across all base pages or map multi-page overlays one to one, compute a centered aspect-ratio-preserving fit from each page box, draw embedded overlay artwork above the base at the selected opacity, and serialize one new PDF.

Frequently asked questions

How are overlay pages matched to base pages?
A one-page overlay repeats on every base page; a multi-page overlay maps page by page and leaves unmatched later base pages unchanged.
What happens when page sizes differ?
The overlay is proportionally fitted inside and centered on the base page, without stretching or cropping.
Does an opaque overlay securely remove the base content?
No. It can hide content visually but does not delete the underlying base page content and is not redaction.
Are either PDFs uploaded?
No. Both inputs are loaded, embedded, drawn, saved, and downloaded locally in the browser.

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