Protect and label your documents with a text watermark
A watermark answers the question a bare document can't: what is the status of this file, and whose is it? “DRAFT” stops a half-finished contract from being signed. “CONFIDENTIAL” reminds every reader — and every screenshot — that a document wasn't meant to wander. A company name across each page discourages competitors from passing your proposal off as their own. This tool stamps a customisable text watermark diagonally (or horizontally) across every page of your PDF, with full control over wording, size and transparency, processed entirely on your device.
How to watermark a PDF
- Drop your PDF into the tool.
- Type the watermark text —
CONFIDENTIAL,DRAFT,SAMPLE, your company name, anything. - Tune the opacity slider (15–25% reads clearly without burying the content) and the font size.
- Keep the 45° diagonal for the classic look, or untick it for a horizontal stamp. Click Add watermark.
Getting the balance right
A good watermark is visible at a glance yet never fights the text underneath. Three rules of thumb: first, grey beats black — the tool uses a neutral grey that shows on both white and tinted backgrounds. Second, opacity below 30% keeps body text comfortably readable; above that, the stamp starts to shout. Third, size to the page: 48 pt suits A4 documents, while slide-style landscape pages can take 60–80 pt. The diagonal orientation isn't just tradition — slanted text is much harder to crop out or clone-stamp away than a horizontal line sitting in a margin.
What a watermark does and doesn't protect
Be realistic about the threat model. A watermark is a deterrent and a label, not encryption: it prevents honest mistakes (signing a draft, forwarding an internal version) and makes misuse legally awkward, because the claim “I didn't know it was confidential” collapses when the word is printed across every page. A determined bad actor with editing software can still attack it — which is why the stamp is drawn into the page content itself rather than added as a removable annotation layer, making casual removal genuinely difficult.
Useful wordings
- Status: DRAFT, FINAL, SUPERSEDED, FOR REVIEW ONLY
- Restriction: CONFIDENTIAL, INTERNAL USE ONLY, NOT FOR DISTRIBUTION
- Ownership: © Your Company 2026, Prepared for Client X
- Validity: SAMPLE, VOID, UNCONTROLLED COPY WHEN PRINTED
Stamp once, and the message travels with the file through every forward, print-out and screenshot — silently doing its job on every page.
Quick reference
| Property | Detail |
|---|---|
| Input | One PDF file + your watermark text |
| Orientation | 45° diagonal (default) or horizontal |
| Opacity | 5–60% (recommended 15–25%) |
| Font size | 10–140 pt (48 pt suits A4) |
| Colour | Neutral grey — readable on any background |
| Permanence | Drawn into page content, not a removable layer |
| Processing | 100% in-browser, no upload |
Frequently asked questions
Can recipients remove the watermark?
Not casually. The stamp is drawn into the page content itself rather than added as an annotation, so it can't be deleted with a click. Determined editing software could attack it, but a watermark's real job — preventing honest misuse and proving intent — is done the moment it's visible.
Will the watermark make my text hard to read?
Not at sensible settings. At 15–25% opacity in grey, body text stays fully readable while the watermark is clearly visible. Preview the downloaded file; if it feels heavy, re-run the original at lower opacity.
Can I watermark only certain pages?
The tool stamps every page, which is what status and confidentiality marks require. To watermark a subset, split those pages out first with the Split PDF tool, stamp them, then merge everything back.
Does watermarking change quality or file size?
Quality is untouched — your original content is preserved beneath the stamp. File size grows only by a few kilobytes, since the watermark is just text drawing instructions.