What a watermark is for
A watermark is a large, faint label printed across a page. It tells anyone who sees the document what it is: a DRAFT that is not final, a COPY that is not the original, a CONFIDENTIAL file that should not be shared, or a SAMPLE that has not been paid for. It also makes screenshots and printouts carry the same message.
The tool adds your text to the pages of the PDF in your browser. The document is not uploaded.
How it works
For each page, the tool works out the size of your text at the chosen font size, then draws it with the colour and transparency you picked. Transparency means the page underneath shows through, so contracts and reports stay readable. The text is written into the PDF as real text in Helvetica, so it stays sharp at any zoom.
Letters that Helvetica cannot show, such as Arabic, Urdu, Devanagari, Cyrillic or Chinese characters, are drawn by your browser into a transparent image at four times the needed resolution, and that image is placed instead. Either way, the live preview shows the result on your first selected page.
The three layouts
| Layout | What it looks like | Good for |
|---|---|---|
| Diagonal | One line from the bottom-left corner towards the top-right | The classic DRAFT or CONFIDENTIAL stamp |
| Centre | One line in the middle at the angle you choose | A calmer label, such as COPY |
| Tiled | Repeated in rows across the whole page | Proofs and samples that should be hard to crop |
The diagonal angle depends on the page shape. On a portrait US Letter page (612 × 792 points) it is:
If the text is too long to fit along the diagonal at your font size, it shrinks automatically to 90% of the diagonal length, so it never runs off the page.
Worked example
You are sending a 6-page proposal to a client for comments and want every page clearly marked as a draft.
- Choose the PDF and type
DRAFT. - Keep Diagonal, set the font size to 90, choose red, and set opacity to 20%.
- The preview shows a large, pale red DRAFT across page 1, with the text underneath still readable.
- Keep All pages, click Add watermark, and download
proposal-watermarked.pdf.
To mark only the pricing pages, say 4 and 5, choose Selected pages and type 4-5. The preview switches to page 4.
Choosing good settings
- Opacity: 15–30% for text-heavy pages; up to 50% for photos and image proofs.
- Colour: grey is discreet, red is urgent, blue looks official. Very dark colours at high opacity hide the content.
- Size: 60–100 points for a single diagonal word on Letter or A4; 24–36 points for tiled text.
- Tiled text: shorter words tile better. “SAMPLE” covers a page more evenly than a long sentence.
Limits worth knowing
A watermark is a visible label, not a lock. Anyone with PDF editing software could delete or cover it, and it does not stop copying or printing. If the document must stay private, also add a password with Protect PDF. If you need to show who approved the document, add a signature with Sign PDF, and for long documents stamp page numbers with Add Page Numbers.
Password-protected files must be unlocked first with the password you know. The watermark is added on top of any existing content, form fields keep working, and bookmarks are kept.