Add Watermark to PDF

Mark Your Documents Before They Leave Your Hands

A proposal goes to a prospect before the deal is closed — you want DRAFT visible on every page. A preview of creative work goes to a client who hasn't paid yet — your logo watermark needs to be there. A sensitive report is distributed internally — CONFIDENTIAL should appear diagonally across each page.

Watermarks communicate status, assert ownership, and deter misrepresentation. This tool applies them to every page of your PDF using customizable text or your own logo image — processed entirely in your browser, never uploaded.

Text vs. Image Watermarks

Text watermarks are fast to set up — type your text (DRAFT, CONFIDENTIAL, SAMPLE, your company name) and customize font size, color, opacity, and rotation angle. A diagonal layout at 45° covers the page most effectively for protection purposes.

Image watermarks let you use your company logo, signature, or graphic as a semi-transparent overlay. Upload a PNG with a transparent background for the best result — the logo appears over the page content without a white rectangle around it.

Opacity as a Design Decision

Opacity is the most important setting. Getting it right depends on what the watermark is for:

10–20% opacity — subtle branding. A company logo at this opacity is present but doesn't interfere with reading. Used on client-facing documents where you want brand presence without obscuring content.

30–50% opacity — visible marking. "SAMPLE" or a logo is clearly visible at normal viewing distance. Content remains readable underneath.

60–80% opacity — strong security marking. CONFIDENTIAL or DRAFT at this level is unmistakable. The underlying content is still legible but the watermark dominates.

90–100% opacity — opaque stamp. Used for very specific cases where the watermark is meant to fully obscure content beneath it (less common).

How Watermarks Are Applied

The tool uses pdf-lib to modify PDF page content streams directly — it doesn't re-render pages as images (which would degrade text quality and remove selectability).

For text watermarks:

• A font (Helvetica by default) is embedded in the document
• The text dimensions are calculated to center it correctly
• page.drawText() applies the text with the specified opacity, rotation, and color to each page

For image watermarks:

• Your PNG is embedded using pdfDoc.embedPng()
• It's scaled relative to the page size and positioned as specified
• page.drawImage() applies it with your chosen opacity

Because this process directly modifies page content (rather than rasterizing the whole document), the output PDF retains selectable text and vector graphics on the original pages, with only the watermark layer added on top.

Real-World Uses

Law firms and consultants stamp draft agreements, settlement proposals, and internal analyses with DRAFT or PRIVILEGED before sharing for review. The watermark signals that the document isn't final and shouldn't be acted upon without confirmation.

Photographers and designers watermark preview images converted to PDF before sending client proof sets. The visible logo protects work that hasn't been paid for yet.

Publishers track review copy leaks by watermarking pre-publication PDFs with the reviewer's name. If an unauthorized copy appears online, the source can be identified.

Businesses brand every outgoing document — proposals, reports, invoices — with a logo watermark for visual consistency and professional presentation.

Educators mark exam papers and assessment materials with DO NOT DISTRIBUTE before sharing digital copies.

Best Practices

Use diagonal text at 45° for protection watermarks. A corner-positioned horizontal watermark is easy to crop. A diagonal spanning the full page requires cropping out useful content to remove.

Test on a single-page extract first. For a 40-page document, use Split PDF to extract one page, apply the watermark, verify the look, then apply to the full document.

Use PNG with transparent background for logo watermarks. A JPEG logo brings a white rectangle with it — the transparent background of a PNG blends seamlessly with any page color.

Optimize your logo PNG before using it. Large PNG files applied across many pages increase output file size. Use a compressed PNG at the display size you need — you don't need a 5000×5000 pixel source image for a corner logo.

After watermarking, protect the PDF if redistribution is a concern. A watermark is a deterrent, not a hard lock — use Protect PDF to add password protection as an additional layer.

Limitations

Watermarks can be removed with professional PDF editors. A text or image watermark added to a PDF's content stream can be stripped using Adobe Acrobat Pro or similar tools. It deters casual misuse but isn't a cryptographic barrier. For strong access protection, combine with password-based encryption.

Encrypted PDFs can't be watermarked until unlocked. Remove the password with Remove PDF Password first, apply the watermark, then re-protect.

JPEG images are not suitable as watermark sources. JPEG has no transparency channel — your logo will appear with a white background. Always use PNG for image watermarks.

Text from non-standard fonts isn't available. The tool uses standard PDF fonts (Helvetica, Times New Roman, Courier). Custom typography requires a desktop PDF editor.

Related PDF Tools

• Protect PDF — Add password encryption after watermarking
• Merge PDF — Combine watermarked sections into one document
• Split PDF — Test watermark on a single page before applying to all
• PDF Compressor — Reduce size if the watermarked PDF is large
• Remove PDF Password — Unlock protected PDFs before watermarking

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