Watermark a PDF

Stamp DRAFT, CONFIDENTIAL or any words you like diagonally across every page — in your browser, so the document never leaves your device.

Runs on your device. Your file is never uploaded.

How to add a watermark to a PDF

1
Choose the PDF
Tap the picker and choose the PDF from your phone, tablet or computer. Nothing is uploaded — the file is read into the page itself, which takes a moment on a long document and no time at all on a short one. Once it is read, the tool shows how many pages there are and the button turns on; the watermark goes on all of them.
2
Type the word, or tap a preset
The box starts on CONFIDENTIAL. Tap DRAFT or COPY to switch in one press, or type anything you like — a client name, a date, 'NOT FOR DISTRIBUTION', 'SAMPLE'. The counter under the box tracks the length: 60 characters is the maximum, but the stamp is drawn at one size and is not shrunk to fit, so about 24 characters is what spans the page end to end. Type more than that and the tool says so before you stamp — the ends will sit past the page edges.
3
Set how strong it looks
Drag the slider between 5% and 60%. Low numbers leave a faint grey ghost that never fights with the text underneath; high numbers are impossible to overlook but make dense pages harder to read. Around 18% suits a document somebody still has to work through.
4
Stamp it and download
Press the button and a new PDF appears, named after the original — offer.pdf becomes offer-watermarked.pdf. The word is drawn diagonally across the centre of every page and saved into the file itself, so it shows on screen and on paper, in any reader.
5
Send it on, if you need to
People watermark a document because it is about to go somewhere. If you would rather send a link than an attachment, download the stamped PDF, then upload that file on the home page to get a clean link with a QR code — whoever opens it reads it in their browser with no download and no account. Publishing a link is the one step that needs a free account of your own; the watermarking never does.

Your file never leaves your device

Most online watermark tools upload your document to a server, draw the word there, and hand back a download link. Look at what people actually stamp — a contract before it is signed, a pitch deck going to one investor, a set of photos on approval, a price list for a single client — and that difference matters: the unreleased version sat on somebody else's machine, and you are trusting a retention policy you cannot check.

This tool works the other way round. The page loads a PDF library into your browser, and the file you pick is read into that tab's memory and rewritten there. No request carries your document, nothing is written to storage, and closing the tab is all the cleanup there is. The practical test: load this page, go offline without reloading, and watermark a file anyway — it still works, which would be impossible if a server were doing the work.

The only thing that ever reaches us is the fact that a tool was used — never the file, its name or its contents.

What this tool can't do

Running on your device buys privacy and speed, and it costs a few things. Worth knowing before you start:

40 MB per file. A parsed PDF takes several times its size in memory, and a phone browser kills the tab silently when it runs out. The cap exists so you get a clear message instead of a dead page.
Text only, one fixed position. The word is drawn diagonally across the centre of the page, in grey, at a size set by the page — it is not shrunk to fit the words, so a stamp longer than about 24 characters runs past the edges (the tool warns you first). There is no image or logo watermark, no tiled repeat, no corner placement, and no colour or font picker.
Every page, or none. The stamp is applied to the whole document — there is no “first page only” switch. To mark a single page, split it out, watermark it alone, and merge it back.
Latin-1 characters only. The built-in Helvetica used for the stamp encodes the Latin-1 set — accented letters are fine, but emoji, curly quotes and em dashes pasted from Word, and non-Latin scripts are refused with a message rather than written as a broken file.
A watermark is a label, not a lock. It is real page content, so a determined person with a PDF editor can remove it and a screenshot ignores it. It marks a draft and discourages casual forwarding; it does not control who can open the file.
Password-protected PDFs are refused. An encrypted file is turned away rather than half-processed, because writing a broken copy is worse than saying no. Unlock it in your PDF reader, save an unlocked copy, and watermark that.

Watermark PDF questions

Is my PDF uploaded anywhere when I watermark it?

No. The stamping happens inside your browser tab, using your own device's processor and memory, so the document's bytes never travel to a server. Nothing is queued for processing and there is no copy of your file to delete afterwards. You can prove it: load this page, switch your device to airplane mode without reloading, and watermark a file anyway — it still works, because everything it needs is already in the tab and no server is involved.

Can someone remove the watermark afterwards?

Yes, with effort — and that is true of every text watermark, including the ones Acrobat adds. The word is drawn as real page content, so anyone with a PDF editor can select and delete it, and a screenshot sidesteps it entirely. A watermark is a deterrent and a label, not a lock: it makes accidental forwarding obvious and marks a draft as a draft. If you need to actually restrict access, share the file as a link you can switch off the moment you want it gone, rather than relying on the stamp.

Does the watermark cover up the text underneath?

It is drawn on top of the page in grey at the opacity you choose, so at low settings it reads as a ghost behind the words rather than a block over them. Below about 25% the page stays comfortable to read; above 40% the stamp starts to compete with dense body text. Nothing underneath is deleted or altered — the original text stays selectable, searchable and copyable, the watermark simply sits over it.

Can I watermark only some pages, or put it in a corner?

Not in this tool. Every page gets the same word, drawn diagonally at 45° across the centre — that is the placement that is hardest to crop off and easiest to see at a glance. If you only want it on the cover, split that page out with the Split PDF tool, watermark it on its own, and merge it back with Merge PDF. Corner placement, per-page text and image logos are not supported.

Why does it refuse emoji, curly quotes or non-Latin scripts?

The watermark is drawn with Helvetica, one of the fonts built into the PDF format itself, which is why the output file barely grows and needs no font download. That built-in font can only encode the Latin-1 character set, so an emoji, a curly quote or an em dash pasted from Word, or Hindi, Arabic, Cyrillic or Chinese text cannot be drawn — you get a clear message rather than a broken file. Everything inside Latin-1 works, which includes accented letters: RÉSUMÉ, ENTWURF, BORRADOR and CONFIDENTIEL all stamp normally, as do digits, currency symbols and ordinary punctuation.

Is there a size limit, a watermark on the output, or a sign-up?

There is a 40 MB limit per file, because the work runs on your device: a parsed PDF takes several times its size in memory, and past that a phone browser kills the tab with no message at all. There is no sign-up, no daily cap on how many files you stamp, and nothing of ours is added to the output — the only mark on your PDF is the word you typed. You would only need an account if you go on to turn the result into a shareable link.

When a stamp isn't enough

A watermark labels a document; it does not decide who can open it. If the point is to stop the file spreading, sharing a PDF people can view but not download explains what view-only actually stops and what it cannot. And if you want a real lock on the file itself, how to password-protect a PDF for free walks through the free ways to encrypt it on a Mac, a PC or a phone.

More PDF tools

All free, all in your browser, none of them upload your file.

See every PDF tool — or turn any finished file into a clean link with a QR code from the home page.