Watermark PDF

The watermark is drawn once on each page, centered, on top of the existing content. Your original file is not changed.

1. Drag one PDF onto the box, or click the box to choose it. Password-protected files are rejected.
2. Type the words in Watermark text. The starting text is CONFIDENTIAL, and a short word works better than a sentence.
3. Set Text size (points) from 8 to 300 (default 64) and Opacity (%) from 5 to 100 (default 25).
4. Choose the Direction: Diagonal, rising (45 degrees), Horizontal, Diagonal, falling (-45 degrees) or Vertical.
5. Pick a Color with the color picker. The default is gray, #6b7280.
6. Press Add watermark, check the note, for example "12 pages marked", and download the file, which is named after your original with -watermarked added.

The text is drawn in bold Helvetica. At the default 64 points the word CONFIDENTIAL is roughly 480 points wide, or about 6.6 inches, which fits across an A4 page on the diagonal. If the text would be too wide for the page at the angle you chose, the tool scales it down so it fits, so a long phrase simply appears smaller than the size you set.

Readability depends mostly on opacity and color:

Because the watermark sits on top of the page, not behind it, a high opacity covers what is underneath. Choose a color that contrasts with the page: gray works on white pages, while a light color suits a dark background. Red is a familiar choice for DRAFT.

Typical uses are DRAFT on a document under review, CONFIDENTIAL on an internal report, COPY on a duplicate, and SAMPLE on a preview that is not meant to be used as is. In every case the watermark is a label. It tells readers how to treat the file. It is not protection.

Anyone with PDF editing software can remove or cover a watermark placed on top of a page, so do not rely on it to stop copying or to hide information. If content must not be seen, leave it out of the file instead of covering it.

The tool has honest limits:

• Text only. There is no logo or image watermark.
• It applies to every page. There is no page range.
• Only Latin letters, digits and common punctuation are supported, because the standard font covers Latin-1. Other characters are refused with a message.
• It does not tile or repeat the text. There is one mark per page.

If you plan to number the pages as well, use add page numbers, which draws the numbers in a margin. For tidying a document first, delete PDF pages removes pages you do not want, and rotate PDF fixes pages that are sideways.

After the file is built, open it and look at several pages, not only the first. A page with a dark photograph, a colored header or a table may need a different color or opacity. If the mark is hard to see on one kind of page and too heavy on another, choose a middle value and a medium-tone color.

If the file will be printed, print one page first. Faint watermarks that look fine on screen can vanish on paper, and strong ones can hide fine print. A 20 to 30 percent setting is usually a safe starting point.

Watermarks do not change the page size. To combine several documents into one marked file, join them with merge PDF first and watermark the joined file. The work is done in your browser with the pdf-lib library, and nothing is uploaded.