Add Watermark to PDF — Text or Logo, Free

Add text or image watermarks to PDF pages with position, angle, opacity and tiling, in the browser

Runs in your browser · nothing is uploaded

Drop the PDF to watermark here

Add one PDF (up to 100 MB). Adding another file replaces the current one. Files never leave your browser.

What it does

This tool places a semi-transparent text or logo watermark on the pages of a PDF. Typical uses are marking quotes and proposals with your company name, labelling internal documents CONFIDENTIAL, or stamping COPY on a scan before sending it. A live preview shows the first selected page while you adjust size and position, and one click applies it to every chosen page. The whole job runs in your browser.

How to use

Drop one PDF on the box or press Choose PDF.
Pick Text or Image (logo). Text can have several lines; an image can be one PNG, JPG or WebP.
Set the text size in points (or the image width), colour, opacity and angle. The preview on the right updates a moment later.
Under Layout choose One spot to place it in one of nine positions, or Repeat across the page to tile it with the spacing you set.
To mark only some pages, choose Choose pages and type ranges such as 1-3, 5.
Press Add watermark and download the new PDF.

How it works

Fonts: Latin-only text uses the standard PDF font Helvetica, so no font is embedded. Anything else embeds Noto Sans KR (SIL Open Font License 1.1) as a subset holding only the glyphs you used.
Placement: a single mark stays 4% of the page’s shorter side (at least 12 pt) away from the edges, measured on the rotated shape so a tilted watermark never sticks out of the page.
Tiling: marks repeat across at their width plus the spacing, and down at their height plus the spacing plus one more mark height (so rows of short text do not run together), with every other row shifted by half a step. Pages that would need more than 400 marks get a wider spacing instead.
Ranges: opacity 5–100%, angle −90° to 90° counter-clockwise, as seen on screen.
Libraries: pdf-lib (MIT) writes the PDF, @pdf-lib/fontkit (MIT) handles the font and PDF.js (Apache-2.0) renders the preview.

Examples

Goal	Settings
Large CONFIDENTIAL across the centre	Text, 72 pt, opacity 25%, angle 45°, one spot, centre
Company name tiled over the page	Text `ACME Corp.`, 20 pt, repeat across the page, spacing 60%
Small logo in the bottom-right corner	Image, width 15%, opacity 60%, angle 0°, bottom right
COPY on every page except the cover	Choose pages `2-`, text `COPY`

To add page numbers as well, use Add Page Numbers to PDF; to place a signature or stamp, use Sign PDF.

FAQ

Is my PDF uploaded?

No. The watermark is drawn inside your browser and the PDF never leaves your device. Only when your text contains Korean or other non-Latin letters does the page download the Noto Sans KR font file (about 1.2 MB) from this site, and no document data is sent with that request.

Will non-Latin text show correctly in every viewer?

Yes. Latin text uses the built-in Helvetica font. Text with Korean, Japanese kana and similar letters embeds Noto Sans KR, and only the characters you actually used go into the file, so it usually grows by a few dozen kilobytes. Chinese characters (Hanja) and emoji are not in that font; they are left out and the result tells you which ones.

Does a watermark stop people from copying or editing the PDF?

No. The watermark is drawn on top of the page, and the original text and images stay as they were. It marks where a document came from, but a PDF editor can still remove it. Preventing copying needs security settings, which this tool does not add.

What about rotated or landscape pages?

Each page's rotation is read and the position and angle are worked out as the page is shown, so mixed portrait and landscape documents get the same look on every page.

Which image works best as a logo?

A PNG with a transparent background. JPG and WebP work too, but their white background shows as a box. Images are scaled to at most 2,000 pixels on the long side, and the width is a share of the page width, so pages of different sizes get the same proportion.