Watermark a PDF
Add a text or image watermark to a PDF in your browser. The file is never uploaded, and the output has no watermark from us.
Choose a PDF to watermark
PDF only, up to 50.0 MB and 500 pages. The file is read in your browser and never uploaded.
No account, no upload, no output watermark.
How to watermark a PDF
- Choose a PDF. The file is read locally; nothing is uploaded.
- Pick text or logo, then set the size, colour, opacity and rotation.
- Choose all pages or a range, and turn on “Repeat across each page” if you want a tile.
- Apply the watermark, download the PDF, and open it in your reader to check the position.
Text or image watermark?
Text is the right choice for “DRAFT”, “CONFIDENTIAL”, a buyer’s email, an order number or a creator handle. It is searchable in the PDF, easy to change and does not need an image file. An image watermark is better for a logo or a signature, especially one with transparency.
The trade-off is legibility. A large text watermark at low opacity is visible without destroying the page; a small logo may disappear on a busy scan. Use the preview to judge the size, then check the downloaded file at 100%.
Watermark the preview, not the paid file
There are two useful patterns. The first is a preview: a lower-resolution PDF with a visible mark that deters screenshot theft and makes the source obvious. The paid file is clean and full resolution. The second is a buyer-specific mark: the paid copy carries the buyer’s email or order ID, so a forwarded copy is traceable.
Both are visible deterrents, not access control. A public file URL can still be forwarded, and a determined person can remove a watermark. The stronger pattern is a marked preview plus a paid link that expires or is capped, with the clean master kept separately. See how to sell a PDF online and Unlockable’s pricing.
What a watermark can and cannot do
A watermark is a deterrent and an attribution mark. It makes a document less convenient to reuse and easier to trace. It is not DRM. A determined person can crop, cover or remove it, and a screenshot bypasses it entirely.
It works best alongside a visible preview, a clean paid file and a link tied to the purchase. The watermark handles the visible part; the link handles the access part. Do not claim more than that, and do not treat a watermark as a substitute for a download cap or an expiring link.
Your file never leaves your browser
The tool loads a PDF engine into the page and processes the file with JavaScript. There is no upload request, no server-side copy and no account. The only network requests are the page’s own assets and the engine; the PDF data is not sent anywhere.
If you want to check it, load the page, turn off your network after the engine has loaded, and watermark a PDF. It still works. The same is true of the image watermark tool.
Limitations
- Password-protected PDFs cannot be opened. Remove the password and save a copy first.
- Non-Latin text is not supported by the standard PDF fonts. Use Latin characters or a logo watermark.
- Very large files are capped at 50 MB and 500 pages. A 300-page PDF will take a moment; the progress bar shows the current page.
- Rotated pages can shift a corner watermark. Centre and tiled placements are the most reliable; download the result to check.
- Scanned PDFs are just images inside a PDF. The watermark is drawn on top, so it works, but the result is a raster page with a vector watermark.
Watermarking a PDF you sell
Keep a clean master. Watermark the preview and any buyer-specific copy, not the master you will reuse. If you personalise a copy, use the buyer’s email or order ID, and keep a record of which copy went to which buyer. That is what makes a forwarded file traceable.
For the delivery side, a link that can expire or be capped is a better fit than a public file URL. Unlockable is one option: upload the file, set a price, share one link, and the buyer pays the privacy and security fee on top. See selling online guides for the product context.
Related tools and guides
Use the image watermark tool for photos, or read how to stop customers sharing your download link for the access-control side. The guide to selling a PDF online covers pricing, delivery and the file itself.
Frequently asked questions
- Is this PDF watermark tool free?
- Yes. There is no account, no email and no limit on the number of PDFs. The tool runs in your browser; the PDF is not uploaded to a server.
- Does the downloaded PDF have a watermark from Unlockable?
- No. The only watermark in the output is the one you add. There is no logo, footer or “made with” credit from us.
- Is the PDF uploaded?
- No. The file is read with JavaScript in your browser and the watermarked copy is created locally. You can load the page, disconnect from the network, and process a PDF; that is the simplest way to check the claim.
- Can I watermark only some pages?
- Yes. The Pages field accepts “all”, a single page such as “2”, or a range such as “1-3,5”. The page count is shown under the file name. The same watermark and settings are applied to every selected page.
- Does it work on password-protected PDFs?
- No. A PDF that needs a password to open cannot be read by the tool. Remove the password in your PDF reader, save a copy, and try again. A PDF with permissions but no open password may also fail; the same fix applies.
- Can the watermark be removed?
- A watermark is a deterrent, not DRM. Someone with the right tools can remove or cover it, especially if it is a single small stamp. A tiled watermark is harder to remove; a visible mark on a preview is usually enough. It does not stop screenshots.
- Does watermarking reduce the PDF quality?
- No. The tool draws the watermark onto the existing pages and saves the document; it does not re-render the text or images. The original page content stays as it was, with the watermark added on top.
- Can I use non-Latin text?
- The standard PDF fonts used here support Latin characters only. If the text includes Chinese, Arabic, Cyrillic or another script, the tool will ask you to change it. A logo watermark works for any script because it is an image.
- Can I watermark a PDF I sell?
- Yes, but think about which copy you mark. A visible mark on the preview deters screenshot theft; the paid file can be clean. If you want a buyer-specific mark, add their email or order ID to the paid copy and keep the clean master. A watermark does not replace access control: a public file URL can still be forwarded.
- Can I watermark several PDFs at once?
- Not in this release. Batch processing is planned. For now, the settings stay in place when you choose another PDF, so the repeated part is the file picker rather than the whole form.
- Why is the preview approximate?
- The browser preview is a schematic of the first page, drawn without a full PDF renderer. It is accurate enough to choose a position and opacity, but the final PDF can differ slightly in font metrics and page rotation. Download the result and check it in your PDF reader.