Watermark PDF
Add a text or image watermark to a PDF and see it on the page as you set the font, size, color, opacity, angle and position. Free, no sign-up, and your files never leave your device.
or drop them here
PDF files only, any number and any size. Locked files ask for their password.
Preview
Add a PDF to see it here.
The earlier digital signature no longer validates
This PDF carried a certificate-based digital signature. Adding a watermark rewrites the file, so PDF readers will report that signature as changed.
How it works
A PDF watermark is text or an image placed on the pages of a document, usually faint and at an angle, to mark it as a draft, confidential or yours. This tool adds it with the open-source pdf-lib library as part of each page: the original text stays selectable, nothing is turned into an image and nothing is uploaded.
- Add your PDFs
Choose or drop one or more files. A locked PDF asks for its password, which is checked on this device.
- Design the watermark
Type the text or pick a logo, then set the size, color, opacity, angle and position. The preview is drawn by the same code that makes the file.
- Save
Choose the pages to mark and download the result. Several files come back together in one zip.
The options, explained
Position, tiles and margin
Pick one of nine spots, from the top left corner to the bottom right, or choose Tiled to repeat the watermark across the whole page in staggered rows. The margin is the distance from the page edge in points (72 points make an inch), measured to the edge of the turned watermark, so a stamp at 45 degrees in a corner still stays inside the margin. Positions follow the page as a reader sees it, so rotated and landscape pages are marked the right way up.
On top or behind the content
On top is visible on every kind of page. Behind content draws the watermark first, so the page's own text and pictures sit over it and stay easy to read. A scanned page is one big picture, and some PDFs paint a white background, so a watermark behind them is hidden. The preview shows which case you have.
Fonts and characters
The eight font choices are the standard PDF fonts (Helvetica, Times and Courier) that every PDF reader has built in, so no font file is added. They cover English and most Western European letters. For other scripts, such as Chinese, Korean, Arabic or Cyrillic, save the text as a PNG image and use an image watermark.
Where your files go
Nowhere. The page loads its code from airusk.com (pdf.js to show the pages, pdf-lib to write the new file) and then works on your PDFs in this browser tab. No file, page or password is sent to a server, and closing the tab clears everything.
A watermark labels a document, it does not lock it
The watermark is part of each page, so it shows in every PDF reader and prints with the page, and it is tagged as a watermark so screen readers can skip it. Anyone with a PDF editor can still select and delete it, as with any watermark, so also control who receives the file when its content is sensitive.
Frequently asked questions
How do I add a watermark to a PDF for free?
Choose your PDF above, type the watermark text or pick an image, and set the size, color, opacity, angle and position while the preview shows the page. Then select Add watermark and download the file. There is no sign-up, no limit on files or pages, and no mark of ours on the result.
Are my PDF files uploaded to a server?
No. Your browser reads and changes the PDF on your device, and nothing is sent anywhere, which makes the tool safe for confidential documents. Once your first file has opened, it keeps working without an internet connection, except for reading a HEIC or TIFF image as the watermark.
Can I watermark only some pages?
Yes. Type the pages in the Pages to mark field, for example 1-3, 5, 8- (8- means page 8 to the end). Leave it empty to mark every page. Pages you leave out are saved unchanged.
Will the watermark make my PDF bigger or blurry?
No. The original pages are kept as they are; nothing is converted to an image or compressed again. A text watermark usually adds a few hundred bytes per page, and an image watermark is stored once and reused on every page, so marking 100 pages adds little more than marking one.
Can someone remove the watermark?
The watermark is drawn into the page, so it shows and prints everywhere, but anyone with a PDF editor can still select and delete it, as with any watermark. Use it to label a document and discourage copying, and control who gets the file when the content is sensitive.
Can I watermark a password-protected PDF?
Yes. You are asked for the password, which is checked on your device. The watermarked copy is saved without the password, so protect it again in your PDF app if you need to.