About this tool
A PDF watermark is text or image overlaid on every page of a PDF, typically used to mark documents as DRAFT / CONFIDENTIAL / COPY, or to brand client deliverables. The mark can be placed diagonally across the page, tiled, or in a corner.
This tool adds watermarks in-browser using pdf-lib. Pick text or upload a transparent PNG, set opacity, position, rotation, and apply across all pages or a specified range.
How it works
Open the PDF
Drop the file.
Pick watermark type
Text (custom string) or Image (transparent PNG).
Set placement
Diagonal across page, Tile (repeated), or Corner. Adjust rotation, opacity, font.
Apply and download
The watermarked PDF saves to your device. Original is untouched.
Use cases
DRAFT documents
Diagonal "DRAFT" at 30% opacity across every page makes the version status unmistakable.
Confidential contracts
"CONFIDENTIAL" tile watermark deters screenshot leaks.
Client deliverables
Brand the deliverable with a corner logo so the client knows where it came from if it gets shared.
Copyright protection
"© 2026 [Name]" diagonal across every page of a PDF book preview.
Format and spec details
| Watermark types | Text (custom font / color / size) or Image (transparent PNG) |
|---|---|
| Placements | Diagonal, Tile, Corner (TL/TR/BL/BR), Center |
| Opacity | 0-100% |
| Scope | All pages or specific page ranges |
Tips and best practices
- 30% opacity is the photographer-standard - visible without dominating.
- Diagonal watermarks are harder to crop out than corner ones.
- Tile watermarks (repeated marks) are nearly impossible to remove cleanly.
How to use the PDF Watermark
The PDF Watermark is a browser-based tool that runs entirely on your device. Inputs you enter never reach a server - all calculations happen client-side in JavaScript. This means:
- Privacy: nothing is logged, sent, or stored by 3Tej. Inputs disappear when you close the tab.
- Speed: results update as you type. No network round trip.
- Offline use: once the page is cached, it works without internet.
- No signup: no account, no email, no rate limits.
Step by step
- Enter your inputs in the form above. Each field is labeled with its unit (currency, percent, kg, etc.) and the expected range.
- Read the result as it updates. The number reflects the formula commonly accepted in PDF Watermark-related calculations.
- Adjust to see sensitivity: change one input at a time and watch how the output moves. This is the fastest way to understand which variable matters most.
- Copy or screenshot the result for later reference. The page state persists for the session if your browser allows it.
When you would use this
- Quick estimates: when you need a number now and don't want to open a spreadsheet.
- Sensitivity analysis: testing how a result changes as inputs vary, before committing to a real-world decision.
- Comparison: running the same calculation with different inputs to compare options side by side.
- Learning: building intuition for how the underlying math behaves.
- Documentation: capturing a snapshot of inputs and outputs at a point in time.
Privacy and offline operation
Every operation in this tool runs client-side using your browser's built-in APIs (Canvas, Web Audio, WebAssembly). No data is uploaded. After the initial page load you can disconnect from the internet and the tool keeps working.
We use Google Analytics and AdSense for the page itself, but neither sees the content of the files you process.
Frequently asked questions
Can a PDF watermark be removed?
A skilled editor can remove single-corner watermarks with content-aware fill. Tiled / diagonal full-page watermarks are much harder. Use tile + 30% opacity for max stickiness.
Should watermarks be over or under content?
Over for "DRAFT / CONFIDENTIAL" stamps. Under for subtle branding. The tool offers both options.
What is the right size?
Text: 80-120 pt for diagonal, 24-36 pt for tile. Image: 30-50% of page width for diagonal, 10-15% for tile.
Is the PDF Watermark accurate?
The PDF Watermark applies the standard formula for pdf watermark. Accuracy is limited only by your input precision. For decisions with material consequences, use the result as a starting point and verify with a qualified professional or the relevant official source.
Is the PDF Watermark free?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads that appear around the tool but not inside the calculation flow.
Are my inputs saved?
No. Inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but does not see what you type into the form.
Can I use the PDF Watermark on my phone?
Yes. The tool is responsive and tested on iOS Safari, Android Chrome, and major desktop browsers. Touch targets meet Apple's 44pt and Google's 48dp minimum guidance.
How do I report a bug or suggest improvement to the PDF Watermark?
Email hi@3tej.com with the URL of this page and a description of what you saw vs expected. We typically respond within 72 hours and update calculators when rules or formulas change.
How accurate is the PDF Watermark?
It applies the standard formula. Accuracy is limited only by your input precision. For decisions with material consequences (taxes, medical, legal, structural), use the result as a starting point and verify with a qualified professional in the relevant field.
Is the PDF Watermark free to use?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads around the tool but not inside the calculation flow.
Are my inputs saved anywhere?
No. All inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but the analytics never see what you type into the form.
Does the PDF Watermark work offline?
Yes. Once the page has loaded, it works without internet. The calculation runs in JavaScript on your device.
Can I share results from the PDF Watermark?
Take a screenshot or copy the output. The page doesn't generate shareable URLs for specific calculations - inputs stay in your browser only.
Why are the results different from another pdf watermark tool?
Most likely: different formula assumptions, different default values, different rounding rules, or different applicable rates. Check the methodology if both tools document it. Both can be valid for different scenarios.