PDF Watermark

Stamp a text or image watermark on every page — diagonal, center, or tiled placement.

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Add a text or image watermark to every page of a PDF — control the opacity, rotation, font, layout (centred, diagonal, or tiled), and position. Useful for branding contract drafts, marking documents 'CONFIDENTIAL' before sharing, or copyrighting a downloadable PDF before it appears on someone else's blog. The watermarking pipeline composites via pdf-lib inside your tab, which means the PDF — including whatever sensitive content it carries — never travels to a server just to gain a watermark.

Next steps

Sign PDF

Draw, type, or upload a signature and click to place it on any PDF page.

Organize pages

Drag pages to reorder, rotate individual pages, and delete pages — then export.

Compress PDF

Compress PDFs to a fraction of their size — perfect for email.

Protect PDF

Lock sensitive PDFs with a password or remove existing protection.

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Runs right inside your browser tab. No uploads. Your files stay private.

How PDF Watermarking Works — Text, Images, and Layout Modes

PDF Watermark stamps a text label or image onto every page of a PDF using pdf-lib. The watermark is written directly into each page's content stream as native PDF objects — vector text for the text watermark, an embedded XObject image for picture watermarks. This makes it part of the document rather than a removable annotation layer. pdfjs-dist renders thumbnails so you can preview placement before exporting.
Text watermarks accept any string (CONFIDENTIAL, DRAFT, DO NOT COPY, an internal version label) and any hex color. Font size ranges from 18 pt to 120 pt. Three layout modes are available. Diagonal places the text rotated 45° centered on the page — the classic legal stamp look. Center renders it upright in the middle. Tile repeats the text across the whole page in a grid, useful for proof images where you want the watermark visible regardless of crop.
Image watermarks accept PNG and JPEG. PNGs with a transparent background are recommended so only the logo or stamp shows through; JPEGs always include a rectangular background. Scale is configurable as a percentage of the image's own size, and opacity ranges from 5 (very subtle) to 100 (fully opaque). 15–25 % is the typical choice for a subtle background watermark; 50–70 % for a clearly visible proof stamp.
The same placement, color, size, and opacity are applied uniformly to every page of the document — there is no per-page or page-range selection, so the watermark is stamped consistently from the first page to the last. A live preview lets you page through the document to check how the watermark lands before you export.
Because the watermark is embedded in the content stream, it cannot be removed by simply deleting an annotation layer. Specialized tools could edit the stream and strip it, but for the typical recipient using a standard PDF viewer it is permanent. Opacity is implemented via a Graphics State (gs) dictionary referencing CA/ca alpha values, which is honored by every modern PDF reader.
Encrypted PDFs cannot be parsed by pdf-lib until they are unlocked, so password-protected files must be cleared first using the PDF Password tool. Existing digital signatures are invalidated by adding a watermark because the page bytes change — this is part of the PDF signing standard.
All of the work happens on the main thread, so browser memory and page count are the practical limits. Small and medium documents watermark in a moment; very large or high-page-count PDFs render their preview thumbnails and apply the watermark synchronously, which can briefly make the tab unresponsive while it finishes. Image watermarks embed the picture once and reference it from each page, so file size grows roughly by the size of the source image plus a small per-page reference cost — typically a few KB for a logo PNG.

Common Use Cases

01

Mark documents as CONFIDENTIAL

Stamp a diagonal CONFIDENTIAL or DRAFT watermark before sharing sensitive documents externally — the standard look for legal redlines and financial drafts.

02

Brand PDFs with your logo

Overlay a company logo at low opacity on reports, proposals, and presentations to reinforce brand identity without obscuring content.

03

Discourage unauthorized copying

Tile a semi-transparent copyright or DO NOT COPY watermark across every page so screenshots and re-shares carry the mark.

04

Identify recipients on shared PDFs

Stamp the recipient's name across each copy so leaks can be traced back to the original audience member.

Frequently Asked Questions

Text watermarks add negligible bytes — a few hundred per page for the content stream additions, using one of the standard built-in PDF fonts so no font data is embedded. Image watermarks embed the image once and reference it from every page, so the increase is roughly the source image size plus a small per-page reference (typically a few KB for a logo PNG).
Not easily. Because the watermark is written into each page's content stream as native PDF objects, it isn't a simple annotation layer that a viewer can hide or delete. Removing it requires editing the content stream with specialized tools like qpdf or Adobe Acrobat Pro.
15–25 % for a watermark that is visible but doesn't obscure content. 50–70 % for a proof stamp intended to be clearly visible. 100 % for an opaque overlay that fully covers the underlying area.
PNG and JPEG. PNGs with a transparent background are recommended for logos and stamps so only the artwork shows through; JPEG always includes a rectangular background. SVG and WebP are not supported — convert them to PNG first.
Not directly — pdf-lib refuses to parse encrypted streams. Remove the password using the PDF Password tool first, watermark, then re-encrypt if needed.
Yes. The watermark is part of the page's content stream and prints at full resolution — it appears exactly as it does on screen. The Graphics State alpha values are honored by every modern print driver.
Not currently — the watermark is applied to every page of the document. To watermark only a subset, first extract those pages (for example with the PDF Organizer), watermark the result, then reassemble if needed.
Yes. Any modification to a signed PDF — including watermarking — invalidates existing digital signatures. This is part of the PDF signing standard and applies to every PDF tool, including Acrobat.
No. pdf-lib writes the watermark and pdfjs-dist renders previews, both inside your browser. The PDF stays in tab memory and is never transmitted.
It depends on the watermark color and opacity. White text at 30 % opacity is usually visible on dark backgrounds; black text at the same opacity disappears. Test on a representative page before applying to a long document.

Step-by-step guide

How to add a watermark to a PDF

Walk through every step with screenshots, format-specific tips, and the platform-by-platform limits you need to know.

Maintained by the WebToolVerse teamLast updated Suggest an edit

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