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Edit & Text

Add a watermark to a PDF, free

Stamp CONFIDENTIAL, DRAFT, SAMPLE, your name or your logo on every page — diagonally, level in the middle or tiled across the page — at the opacity you choose. It is done in your browser, so the document you are protecting is never uploaded to protect it.

Settings appear once you add a PDF.

Watermark
Picture
Placement
20%
Advanced 5
70%
Typeface
Bold
Put it behind the content The text and pictures of the page are drawn over the mark. On scans, whose pages are one solid picture, a mark behind them is hidden.

Done on your device No upload, no queue, no sign-up.

Bytes sent anywhere: 0 B

How to add a watermark to a PDF

Your PDF goes into this browser tab, is stamped with your watermark on your device, and comes back as a watermarked PDF. 0 bytes uploaded

  1. Add your PDFs

    Drop the PDF, or a batch of them.

  2. Check the settings

    Type the text — CONFIDENTIAL, DRAFT, your name — or choose a logo, then pick the placement and how faint it should be. The preview shows page 1 as it will come out.

  3. Save the result

    Save. The watermark is part of every page, in every viewer and on paper.

Why it doesn’t upload

A watermark goes on documents you are worried about: a contract out for review, a portfolio sent to a prospective client, ID copies you have to hand over. Uploading one to a watermark site to protect it defeats the point, so here it is stamped inside your own browser.

Check it in your browser’s Network tab

Worth knowing

  • A watermark discourages copying and shows where a copy came from; it is not a lock. Someone with a PDF editor and patience can remove a mark drawn over a page, so for real protection add a password as well.
  • Text marks use a built-in font. Accented, Greek or Cyrillic letters switch to an embedded font trimmed to just the letters used, which adds a few kilobytes. Chinese, Japanese and Korean text is not supported for text marks yet — use an image of the text instead.
  • “Behind the content” is hidden on scanned pages, because the whole page is one opaque picture. Leave it off for scans.
  • An image watermark is embedded once and reused on every page, so a big logo adds its own size to the file once, not per page.

Under the hood

What happens to your file

Text is drawn with pdf-lib at the opacity you choose, set in an ExtGState so it is real transparency, not a pale color. A logo is embedded once and every page draws the same image, so the file grows by its size only once. “Behind the content” moves the watermark’s content stream to the front of the page’s own, so the page paints over it.

Runs on pdf-lib

Reference: pdf-lib documentation · ISO 32000-2 (PDF 2.0)

Questions

How do I add a CONFIDENTIAL watermark to a PDF?

Drop the PDF, leave the text as CONFIDENTIAL (or type your own), choose Diagonal and press Add watermark. Around 15–25% opacity keeps the page readable while the mark stays obvious.

Can I use my logo as a watermark?

Yes. Switch Watermark to Logo or image and choose a PNG, JPG or WebP. A PNG with a transparent background gives the cleanest result; Center or Tiled usually suits a logo better than diagonal.

Can I watermark many PDFs at once?

Yes. Drop them together and every file gets the same mark. Save them one by one, all as a ZIP, or all into a folder on desktop Chrome and Edge.

Can the watermark be removed?

It is drawn into each page, not added as a comment, so it survives viewers, printing and most editing. It is not tamper-proof, though: someone determined with an editor can remove shapes from a page. Pair it with a password if the file must not be changed.

Does a watermark make the PDF bigger?

Barely for text — a few kilobytes. An image watermark adds the picture’s size once, since the same picture is reused on every page.

Can I watermark only some pages?

Yes. Under Advanced, type the pages, like 1 for the cover only or 2-12 for everything after it.

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