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Protecting proprietary manuscripts, sensitive pre-release proposals, confidential legal drafts, and trademarked photography requires clear visual ownership marking. PDFPK’s Watermark PDF tool lets you stamp customized text watermarks (such as "CONFIDENTIAL", "DRAFT", or your company name) or graphical logo stamps across every page of your PDF with full control over rotation, opacity, and positioning.
Select the PDF file you wish to stamp with a watermark.
Select Text Watermark (custom message) or Image Watermark (upload company logo/PNG).
Set opacity (e.g. 20% to 50%) and angle (e.g. 45° diagonal or horizontal).
Click "Add Watermark" to permanently embed your mark and download your protected document.
Engineered for maximum security, lossless document preservation, and instant client execution.
Stamp customized text watermarks or upload company logo images (PNG, JPG) for branding.
Dial in exact transparency levels so watermarks remain clearly legible without obscuring underlying text.
Rotate text watermarks diagonally (45°) or horizontally (0°) across the center of every page.
Watermarking executes locally in your browser memory. Confidential documents are never uploaded to cloud servers.
Watermarks are embedded directly into the page stream, preventing easy removal by unauthorized viewers.
Stamps hundreds of pages in seconds with zero waiting queues.
In PDF graphics architecture, visual elements are rendered sequentially based on their order in the page `/Contents` stream. An underlay watermark is written before page content, placing it behind text—which can cause it to be hidden by solid background scans. An overlay watermark with an Extended Graphics State (`/ExtGState`) alpha transparency channel draws semi-transparently over page content. PDFPK uses alpha-blended transparency overlays, ensuring that your mark remains clearly visible across all pages without obliterating document readability.
When circulating confidential quarterly financials, M&A due diligence files, or unreleased screenplays to external review committees, stamping diagonal watermarks with specific recipient names or "CONFIDENTIAL DRAFT" drastically discourages unauthorized screen captures and illicit redistribution.
| Input Document | PDF (any version) |
| Watermark Types | Custom Text String or Image (PNG, JPG) |
| Opacity Range | 10% to 100% Alpha Transparency |
| Rotation Angles | 0° Horizontal, 45° Diagonal, 90° Vertical |
| Engine | Client-Side PDF-Lib Vector Engine |
| Privacy | 100% In-Browser Sandboxing |
Stamp "DRAFT - FOR REVIEW ONLY" across preliminary agreements before final signature execution.
Overlay your corporate logo badge in the header or footer of invoices and customer estimates.
Mark digital book sample chapters with "SAMPLE COPY" to prevent unauthorized redistribution.
Stamp course examination papers with instructor credentials to prevent unauthorized student sharing.
Your privacy is our highest priority. Unlike other online document converters, PDFPK processes files locally within your browser sandbox whenever possible. When server-side processing is necessary, files are held ephemerally and automatically purged.
Read our Full Privacy & Data Security PolicyEverything you need to know about functionality, privacy, and file compatibility.
Unlike simple annotation layers, PDFPK embeds watermarks directly into the page content stream. It cannot be clicked or deleted like a standard PDF comment.
Between 20% and 30% opacity is ideal. This ensures the watermark is immediately noticeable while allowing underlying text to be read effortlessly.
Yes! Select the "Image Watermark" option and upload your PNG or JPG logo. Transparent PNGs look especially professional.
Text watermarks add negligible data (only a few bytes per page). Image watermarks add the compressed size of your logo image once to the document resources.
No. Watermarking executes 100% locally inside your browser sandbox, keeping your documents confidential.
Yes, 100% free with no watermarks of our own added!