What a text watermark is good for
A watermark tells every reader, on every page, how a document should be treated. Common uses:
- Status marks such as DRAFT, FOR REVIEW or SUPERSEDED, so an old version is never mistaken for the final one.
- Confidentiality labels such as CONFIDENTIAL or INTERNAL on documents shared outside a secure system.
- Samples and proofs, for example a designer's portfolio piece or a translator's test page marked SAMPLE until it is paid for.
- Copies of identity documents. When a landlord, hotel or employer asks for a scan of your passport, writing the purpose and date across it, such as "Rental application, Oct 2026", makes the copy far less useful to anyone who later tries to reuse it.
How the watermark is drawn
The text is stamped as a single line, centred on every page and rotated around that centre by the chosen angle: 0° for horizontal, 30° or 45° for diagonal, 90° for vertical. It is drawn on top of the existing content, which is why opacity matters: at the default 25%, the page underneath stays fully readable.
The font is DejaVu Sans Bold, embedded in the file with only the characters you used, so it adds very little to the file size. It covers Latin scripts including Turkish and Vietnamese, Cyrillic and Greek. Chinese, Japanese and Korean characters are not in the font and will not display, and right-to-left scripts are not laid out correctly.
The watermark is real text, not a picture. It stays sharp at any zoom and prints cleanly, but it is also picked up by search and text selection, so copying a paragraph from the watermarked file may include the word CONFIDENTIAL in the middle.
Choosing size, opacity and colour
Size is set in points, from 8 to 200; 72 points equal one inch. The size is the same on every page, and the text is never wrapped, so long wording at a large size runs off the page.
Some reference numbers for an A4 page, which measures 595×842 points with a diagonal of about 1,030 points:
- "CONFIDENTIAL" at the default 60 points is about 500 points wide, roughly half the diagonal. Around 90 points fills it more boldly while leaving a margin at the corners.
- A short word such as "DRAFT" fits at 45° even at 150 to 200 points.
- A sentence like "Rental application, Oct 2026" needs to come down to roughly 35 points to fit across the diagonal.
For opacity, 15 to 30% keeps text underneath readable on screen. Pale colours at low opacity can almost vanish on office printers, so for documents that will be printed, go to 30 to 40% or pick a darker colour. Red is the default and reads as a warning; mid-grey looks more neutral on business documents, and blue works well on ID copies, where it stands out from the black text and photo.
All files in a batch get the same settings, and you can download them one by one or as a ZIP.
Making the watermark harder to remove
Because the watermark is a separate text object, anyone with a PDF editor can select and delete it. That is fine for status marks like DRAFT, but not for a passport copy you want to keep from being reused.
To fuse the watermark with the page, turn the watermarked pages into images with PDF to JPG, then rebuild the PDF from those images with JPG to PDF. The text and the watermark then become a single picture, which cannot be cleaned up without retouching. The cost is that text in the document is no longer selectable or searchable, and the file is usually larger.
Two more practical notes. Password-protected PDFs should be unlocked before watermarking, otherwise the output may not open correctly. And if you also want to restrict who can read the result, add the password after the watermark with Protect PDF, not before.
Everything runs in your browser and files up to 100 MB are supported; the document is never uploaded.