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Add Watermark to PDF
Stamp "CONFIDENTIAL", "DRAFT", "COPY", your company name or a logo on every page of a PDF – or just the pages you choose. Your file is never sent to a server: the watermark is added right here in your browser, so contracts, bank statements and ID scans stay on your device.
Choose a PDF, type your watermark and tap Add watermark.
How to add a watermark to a PDF
- Tap Choose a PDF file and pick the document.
- Type the watermark text – CONFIDENTIAL, DRAFT, COPY, SAMPLE or your business name. For a logo, switch to Image (logo) and choose a PNG or JPG.
- Set the position, font size, color, opacity and rotation. The defaults (diagonal, 25% opacity) suit most documents.
- To stamp only some pages, type them in Pages, e.g.
1-3,5. Leave it empty for every page. - Tap Add watermark. A preview of the first stamped page appears; tap Download to save. Not happy? Change a setting and run it again – your original file is untouched.
The watermark is drawn as vector text on top of each page, so the original text stays selectable, copyable and searchable. Pages are not turned into pictures, so nothing gets blurry and the file barely grows (about 1 KB for Latin text).
Choosing position and opacity
| Use case | Suggested settings |
|---|---|
| ID or passport copy for a landlord, bank or visa application | Tiled, 36–40 pt, 20–30% opacity, text like "For ABC Lettings only – Oct 2026" |
| Internal or confidential report | Diagonal, 60–80 pt, 20% opacity, "CONFIDENTIAL" |
| Draft contract or proposal for review | Diagonal, "DRAFT", 15–25% opacity |
| Client proofs, quotes, design samples | Tiled "SAMPLE" or your studio name |
| Logo or branding | Image, bottom right, 15–20% width, 60–100% opacity |
100% opacity is solid; lower values are fainter. For text that must stay readable, 15–30% works well. Rotation is counter-clockwise in degrees. Diagonal follows each page's corner-to-corner angle automatically – about 52.3° on US Letter and 54.7° on A4 portrait.
Behind the content slides the watermark under the page text so it never hides a word. Scanned PDFs are one big picture per page, though, and would hide it completely – use On top for scans.
Fonts and non-Latin text
Text in English and Western European languages (é, ñ, ü, ß and so on) uses Helvetica Bold, one of the fonts every PDF reader has built in, so nothing extra is downloaded. Korean text needs a font embedded in the file: the tool then downloads, once per visit, the font engine fontkit (about 340 KB) and Gothic A1 Bold (about 400 KB, all 11,172 modern Hangul syllables), an open-source font under the SIL Open Font License. Only the characters you actually typed are embedded, so a ten-character Korean watermark adds only about 4 KB.
Other scripts – Cyrillic, Greek, Chinese or Japanese characters, Arabic, emoji – aren't supported yet. Make a PNG of your text in any editor and use it as an image watermark instead.
Things to know
- A watermark is not security. Anyone with a PDF editor can remove it. It marks ownership and discourages misuse; for documents that truly must not leak, limit who receives them.
- The watermark is real text, so copying or searching the page can pick up the watermark words too. Tiled watermarks can end up mixed into copied paragraphs, so prefer center or diagonal for documents people will copy text from.
- Digitally signed PDFs: any change, including a watermark, invalidates the signature. Send the signed original when a signature has to verify.
- Password-protected PDFs can't be processed. Remove the password in your PDF viewer, save a copy and try again.
- On a phone, keep files under about 100 MB – everything happens in your device's memory.
To keep only some pages first, use Split PDF; to bundle several documents into one, use Merge PDF. Photos of documents can become a PDF with Image to PDF.
Frequently asked questions
Is my PDF uploaded to a server?
No. Your PDF is never sent to a server; it is processed entirely in your browser. The page downloads the PDF library (pdf-lib) and, only for Korean text, a font from a public CDN. Close the tab and the file is gone from memory.
Will the original text still be selectable?
Yes. The original page is left as it is and the watermark is added as an extra layer on top (or underneath), so the text can still be selected, copied and searched. Nothing is rasterized.
How do I watermark an ID copy for a rental or visa application?
Choose Tiled and type who it is for and the date, e.g. "Copy for XYZ Property – 19 Oct 2026". A copy marked that way is much harder to reuse for anything else. If your ID scan is a JPG, turn it into a PDF first with Image to PDF.
Does the watermark make the file bigger?
Barely. Latin text adds about 1 KB; Korean text adds a small font subset of a few KB (about 4 KB for ten characters). Tiling repeats the same text, so it stays small. An image watermark adds the image once, however many pages it appears on.
Can I remove a watermark later?
This tool doesn't remove watermarks. Your original file is never changed – the result is a new file – so just start again from the original.
Sources
- PDF creation and editing library: pdf-lib (GitHub)
- PDF file format specification: ISO 32000-1 (PDF 1.7)
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