Add a watermark to a PDF
Choose a PDF, type the watermark text, set how it looks and save a stamped copy. It runs in your browser and nothing is uploaded.
Free · no signup Runs in your browser
How do I add a watermark to a PDF?
Choose the PDF, type the watermark text (such as DRAFT), set the size, angle, colour and opacity, and press Add watermark. The text is stamped across every page, in the middle or repeated as a pattern, and a copy is saved to your downloads. The file is read on your device and never uploaded, and the tool adds no watermark of its own.
What a text watermark is for
A watermark marks a document without changing what it says: DRAFT on a proposal that is not final, CONFIDENTIAL on a report that should not be shared, COPY on a copy of a certificate, or a name on a document sent to one person so that a leak can be traced. It is drawn faintly across the page so that the page stays readable.
Choose a diagonal angle (45 degrees is traditional), a large size and a low opacity, 15 to 30 percent, so the text shows without hiding the words underneath. The tiled option repeats the text over the whole page, which is harder to crop out and better for traceability. Be aware of what a watermark is not: it is drawn onto the page, so someone with a PDF editor can still remove or paint over it. It deters casual copying and labels a document, but it is not security.
It runs in your browser. Your file is never uploaded, and there is no watermark of ours or sign-up.
How it works in detail
The PDF is opened in your browser with pdf-lib. For each page the tool measures your text, places its centre at the centre of the page (or on a repeating grid when 'Repeat across the page' is on) and turns it by your angle. It is drawn on top of the page in the built-in Helvetica font at the size, colour and opacity you set, bold if you choose. Opacity runs from 5% to 100%, so a light, large watermark can sit behind the reading without hiding it. Helvetica supports Latin letters (including accents), digits and common symbols. For pages that are rotated, the position and angle are adjusted so the watermark looks as you set it on the displayed page. The stamped copy is saved; the original is not changed.
How to use it
- Choose the PDF.
- Type the watermark text, such as DRAFT or CONFIDENTIAL.
- Set the size in points, the angle (45 is a diagonal), the opacity (try 0.15 to 0.3) and the colour. Tick Bold or Repeat across the page if you want them.
- Press Add watermark.
- Download the copy and check the pages: a watermark drawn on top cannot be removed from the finished file, so keep your original.
What changes and what stays the same
What the tool does to your file, and what it leaves alone.
| Aspect | What happens |
|---|---|
| Page content | Unchanged underneath; the watermark is drawn on top |
| Watermark | Text only, in Helvetica; same on every page |
| Opacity | 5% to 100%, as you set |
| Selectable text | Stays selectable; the watermark text is added as text too |
| The original file | Never changed: the tool builds a new file and the original stays where it is |
| Privacy | The PDF is read on your device and is not uploaded; there is no account and no watermark |
When to use it
- Marking a document DRAFT or CONFIDENTIAL
- Labelling a copy so it is not mistaken for the original
- Putting a recipient's name on a shared document
- Discouraging casual reuse of a document
Problems you may run into
Most problems come from the file itself, not from the tool.
| What you see | Likely cause | What to do |
|---|---|---|
| 'This PDF is password-protected' | The file is encrypted, so the browser cannot read it | Remove the password in the program that made it (or open and print to a new PDF), then try again |
| 'This file could not be read as a PDF' | The file is damaged, or is not really a PDF (it was only renamed) | Open it in a PDF viewer to check; if it opens there, re-save it as a new PDF and try again |
| The watermark hides the text | Opacity is too high or the colour too dark | Lower the opacity to 0.15 to 0.3 or choose a light grey |
| A character is missing or odd | Helvetica covers Latin letters, digits and common symbols only | Use Latin text, or stamp an image with the watermark image tool |
| The watermark is cut off | The text is too large for the page or the angle | Reduce the size or use a smaller angle |
| I want a logo, not text | This tool stamps text | Use the watermark image tool for pictures |
Mistakes it helps you avoid
- Making the watermark so strong that the page cannot be read: keep opacity low.
- Relying on a watermark as security: it can be removed.
- Using characters the built-in font cannot draw, such as other alphabets.
- Stamping the only copy: keep your original.
How it works
Your PDF is read and rewritten inside your browser.
1. The PDF is opened in your browser with pdf-lib.2. The text is measured and placed so its centre is at the centre of each page (or on a repeating grid), turned by your angle.3. It is drawn in Helvetica at your size, colour and opacity, on top of the page.4. The stamped copy is saved. The original is not changed. Nothing is uploaded.
The text is drawn with the built-in Helvetica font, so it supports Latin letters (including accents), digits and common symbols. Opacity runs from 5% to 100%. For pages that are rotated, the position and angle are adjusted so the watermark appears as you set it on the displayed page.
Example: a draft proposal
You stamp DRAFT in grey across a 6-page proposal.
- TextDRAFT
- Size and angle110 points at 45 degrees
- Opacity20%
A six-page copy with a faint diagonal DRAFT on every page
Tick 'Repeat across the page' for a pattern.
Terms on this page
- Watermark
- Text or a picture drawn faintly on a page to label it.
- Opacity
- How solid the watermark is: 1 is solid and 0 is invisible.
Common questions
Can the watermark be removed?
Yes, by someone with a PDF editor. It labels a document but is not a security feature.
Can I use my own text?
Yes. Type any text using Latin letters, digits and common symbols.
Can it be diagonal?
Yes. Set the angle, 45 degrees is the usual choice.
Is my PDF uploaded?
No. Your browser reads the file on your own device, changes it and saves the result. Nothing is sent over the network.
Can it open a password-protected PDF?
No. Remove the password first, then try again.
What to work out next
Where these numbers come from
- pdf-lib — create and modify PDF documents in any JavaScript environment (MIT licence) The open-source library used to draw text on the pages in your browser.
- Adobe — PDF 32000-1:2008 (ISO 32000-1), the PDF specification Page coordinates in points, the standard fonts and page rotation.
- MDN Web Docs — Using files from web applications How a page reads a file you choose without uploading it.
Last verified 2026-10-25 The method on this page is checked against the sources above at least once a year. Spotted something out of date? Tell us and we will fix it.
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