Add Watermark to PDF

What this PDF watermark tool does

Drop a PDF and stamp a watermark across its pages. Text mode takes any phrase — CONFIDENTIAL, DRAFT, DO NOT COPY, a client name, a date — with a choice of font, size in points and color. Image mode takes a logo or signature in PNG (transparency kept), JPEG, WebP, GIF, BMP, AVIF or SVG and scales it as a percentage of the page width. Either kind can sit once in the center of the page or be tiled in a staggered pattern that covers the whole sheet, at any angle from −90° to 90° (45° diagonal is the classic), with opacity from 5 % to 100 %. Restrict it to selected pages with ranges like 2- or 1-3, 7. The preview re-renders the first affected page after every change, so what you see is the actual output.

The watermark is drawn with pdf-lib as real PDF content — vector text in the built-in standard fonts, or an image XObject embedded once and shared by every page, so a logo on 300 pages costs the file one copy of the logo. Nothing is rasterized and the original page content is untouched. The default blend mode, Multiply, makes the watermark look printed into the paper: it tints white areas but never covers black text, so the document stays perfectly readable. Everything runs in your browser; no upload, no watermark of ours, no page limit.

How to use it

Drop or choose a PDF. Pick Text or Image. For text, type the phrase and set font, size and color; for an image, click Choose image and set its width as a share of the page. Choose Centered (one stamp per page) or Tiled (repeated across the page), drag the angle and opacity sliders, and enter page ranges if only some pages should be marked. Watch the preview, then press Add watermark and download yourfile-watermarked.pdf. In Tiled layout two sliders set the horizontal and vertical gap as a percentage of the watermark's own size, so density stays the same when you change the font size or logo, and Staggered rows offsets every other row by half a step.

Text that the standard PDF fonts cannot draw — Chinese, Japanese, Korean, Cyrillic, Greek, Arabic — still works: the tool renders it with your browser's fonts into a crisp transparent image and embeds that instead, which is noted under the text box when it happens. Your settings are remembered on this device. The marked file can continue to Merge PDF, Compress PDF or PDF to image; to add page numbers as well, run Add page numbers afterwards. To place a handwritten signature instead of a repeated mark, use Sign PDF.

Common pitfalls

A watermark is not security. It is drawn as ordinary page content and any PDF editor can remove it. Use it to label, deter and attribute, not to protect — for protection you need encryption and permissions. Too dark or too opaque a watermark makes the document unreadable and, on scans, hides handwriting; 30–50 % opacity in mid gray is the usual sweet spot, and Multiply keeps text legible even at 100 %.

Multiply has one side effect: on dark page backgrounds a light watermark disappears, because multiplying by black gives black. Switch the blend to Normal for white or bright watermarks on dark designs. Tiled layouts with a very small font or logo can produce hundreds of stamps per page and grow the file — raise the size or use Centered. Password-protected PDFs cannot be modified; remove the password first. The watermark inherits each page's orientation, so sideways-stored scans still get a correctly oriented stamp.

Background: how a watermark lives inside a PDF

A PDF page is a content stream of drawing operators. Adding a watermark appends a few operators — set an extended graphics state with the chosen opacity and blend mode, apply a rotation matrix, show text or paint an image — to that stream. Text uses one of the fourteen standard fonts every reader must ship, so no font is embedded; an image is stored once as an XObject and referenced from every page that uses it. That is why a 200-page file with a logo watermark grows by roughly the size of one logo plus a few hundred bytes per page.

Transparency and blend modes are part of the PDF 1.4 transparency model and are rendered by every modern viewer, including browsers, Preview and Acrobat. The position is computed in the page's visual coordinate system — its crop box, adjusted for any /Rotate flag — so a stamp centered on screen is centered on paper too. The preview is the real thing: the first affected page is extracted, watermarked with pdf-lib and rendered with pdf.js, the same engine Firefox uses to display PDFs. The page works offline once loaded.

When you need to watermark a PDF

Marking a proposal, quote or manuscript CONFIDENTIAL or DRAFT before it circulates. Putting a client's name and the date on every page of a report so leaked copies can be traced. Stamping SAMPLE across a template, a mock exam or a preview of paid material. Adding a company logo to invoices, certificates or letters produced by software that cannot. Labelling copies of ID documents — for bank use only, dated — which is exactly the kind of file you do not want to upload anywhere.

On this site the usual flow is: merge or organize the pages, add the watermark here, number the pages, and compress if the file has to fit an email limit. Need a watermarked page as a picture for a slide or a message? PDF to image renders it, watermark included.

Frequently asked questions