MultiKit

Add a Watermark to a PDF: Text, Opacity and Angle, No Upload

  • Free
  • No sign-up
  • Runs in your browser
  • Version 1.0.0
  • Last updated 2026-10-26
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Stamp a PDF with a text watermark such as CONFIDENTIAL, DRAFT or a name. See a live preview, choose the pages, and save. The file never leaves your device.

Everything you enter is processed in your browser and is never sent to a server.

Browsers:Chrome119+Edge119+Firefox121+Safari17.4+Opera105+Samsung Internet25.0+Browsers

How to use

  1. Drop your PDF onto the box, or choose it. A preview of the first marked page appears.
  2. Type the watermark text. Any language works, including Korean. Then set the width, opacity and turn, and pick a color.
  3. Choose One in the middle, or Repeated across the page for a tiled pattern. To mark only some pages, write them in Pages to mark, such as 1-3, 5; leave it empty for every page.
  4. Press Add watermark and save. You get a copy of the PDF with the watermark added, named like your file with -watermarked at the end.

Examples

A 10-page PDF, text CONFIDENTIAL, Pages to mark left empty
→ All 10 pages carry the watermark, once each, in the middle of the page
The same PDF, Pages to mark 2, 4
→ Only pages 2 and 4 carry the watermark; the other pages are unchanged
The same PDF, Repeated across the page, turn 45
→ Each marked page gets many copies in a staggered grid, all turned together
The page's text stays as it was; the watermark is added on top.

How it works

The watermark is text drawn by your browser into a see-through picture, which the open-source pdf-lib library, in its maintained @cantoo fork, then places on each chosen page with the opacity and turn you set. Drawing it in the browser is what lets any language work, because a PDF’s built-in fonts cannot show Korean or most non-Latin letters. The picture is stored once and reused, so many pages do not mean many copies of it.

The width is a share of the page width, so the same setting looks the same on a small page and a large one. The position is measured on the page as it appears on screen, from the visible area and after any rotation, so a watermark in the middle stays in the middle of a sideways page too. A repeated watermark is laid out in a staggered grid that is turned with the watermark, and a page never gets more than 600 copies.

The tool is tested by building PDFs with known text, marking all pages and only the pages named, repeating the watermark, and marking pages that are turned or cropped, then reading the results back to check that the page text is unchanged and that the right pages carry the picture.

Sources

Frequently asked questions

How do I add a watermark to a PDF?
Open the PDF here, type the text, adjust the look and press Add watermark and save. The preview shows the result before you save.
Can the watermark use Korean or other languages?
Yes. Your browser draws the text, so any language it can show works, and the result is placed on the page as a see-through picture.
Can someone remove the watermark?
A watermark discourages casual copying, but it is not protection. It is a picture on top of the page, so it cannot be selected as text, yet anyone with PDF editing software can still cover or remove it.
Can I put it on only some pages?
Yes. Write the pages in Pages to mark, such as 1-3, 5, or 8- for page 8 to the end. Empty means every page.
Does the file get much bigger?
Not by much. The watermark picture is stored once in the file and reused on each page it appears on.
Are my files uploaded?
No. The PDF is read and edited in your browser, so private documents stay on your device.
Is there a limit?
Up to 500 pages and 100 MB for a file. A PDF protected by a password has to be unlocked first with the program that protects it.
Version history
  • 1.0.0 — First release.

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