HelperCratePDF Watermark
Stamp diagonal text across every page of a PDF, with size, color and opacity control.
Your files never leave your device. Everything runs in your browser.
What PDF Watermark does
PDF Watermark stamps diagonal text across every page of a PDF — short phrases such as CONFIDENTIAL, DRAFT or a client name. The result is a new copy; the original file is untouched.
It is used before drafts leave a team, for marking internal documents, labelling proofs, or adding a visible reminder that a file should not be circulated. Because the mark is drawn onto the page itself, it appears in every PDF viewer and on every print.
The tool draws a classic 45° text stamp with pdf-lib and gives you control over the wording, size, colour and opacity. Everything runs in your browser.
How to use PDF Watermark
- Drop a PDF onto the dropzone.
- Type the Watermark text — shorter phrases look better than full sentences.
- Choose a font size between 8 and 200 (60 is the default) and pick the colour with the colour picker.
- Set the Opacity % between 5 and 100 (25 is the default); lower values sit more discreetly behind the content.
- Click Apply watermark. The page count is reported and the watermarked PDF downloads automatically.
Features
- A 45° diagonal text stamp in the same position on every page.
- Controls for wording, font size (8–200), colour and opacity (5–100%).
- Opacity is clamped to the supported range, so extreme entries still produce a valid PDF.
- Blank text falls back to WATERMARK instead of stamping an empty string.
- Draws with the built-in Helvetica Bold font, which covers Latin text.
- Runs locally with pdf-lib; the document is never uploaded.
Tips and common mistakes
- Keep the phrase short and the opacity low for a professional look; heavy full-opacity stamps make documents hard to read without adding much protection.
- A red stamp at 20–30% reads clearly as confidential while leaving the text underneath intact.
- Keep the clean original for your own records — the tool always produces a separate watermarked copy.
Frequently asked questions
Can the watermark be removed?
The stamp is ordinary PDF text drawn onto the page, so a PDF editor can select and delete it. Treat a watermark as a visible label and reminder, not as a security control — if a document must not be shared, restrict access to the file itself.
Will the watermark cover important text?
At the default 25% opacity it sits lightly over the content and the underlying text stays readable. For busy pages, pick a lighter colour or lower the opacity; raise it when the point is to make the document awkward to reuse.
Can I use a company name or a date instead?
Any short text works. Keep it brief: the phrase is drawn at the chosen size across the page, so very long strings can run past the page edges.
Which characters are supported?
The built-in Helvetica Bold covers basic Latin letters, digits and punctuation, plus common accented characters. Scripts such as Arabic, Hebrew or CJK are not available with this font and will not render.
Does it work on scanned PDFs?
Yes. The watermark is added as a new text layer on each page, whether that page contains selectable text or a scan.
Can I watermark only some pages?
This tool stamps every page. If the document needs different marks on different pages, split the file first with Split / Extract PDF, watermark the parts separately, and merge them again.
Related pdf tools: PDF Page Numbers, Sign PDF, Image Watermark, PDF Metadata Editor.
The watermark is drawn locally with pdf-lib; the PDF never leaves your device.