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Watermark PDF Online
Use this free tool to watermark a PDF online without uploading it anywhere. Stamp a word like CONFIDENTIAL, DRAFT or your own name across every page — diagonally, tiled over the whole page, or as a quiet strip along the bottom. You control the opacity, size and colour, and the watermarked copy downloads in seconds, made entirely in your browser.
For the bottom-strip layout the size is capped at 14 pt so the strip stays a strip.
Nothing leaves your device. Your PDF is watermarked locally in your browser with the pdf-lib library stored on this site — no upload, no server, no copy kept anywhere.
How to use this tool
- Click the drop box (or drag your PDF onto it). The box confirms your file name and size.
- Type your watermark text — a status word, your name, or your business name.
- Choose the layout: one diagonal stamp, a tiled repeat, or a bottom strip.
- Set the opacity with the slider, then the size and colour.
- Press Add Watermark. Your watermarked PDF downloads automatically.
How it works
A watermark is simply extra text drawn onto a page with a transparency setting, so the page underneath shows through. This tool opens your PDF with the pdf-lib library — stored on this website, running in your browser — and draws your text on every page with the opacity you picked, expressed as a number between 0 and 1:
Placement depends on the layout. For the diagonal, the tool measures your text in the chosen font, centres it on the page and rotates it by −45 degrees, the angle readers recognise instantly. For the tiled layout it repeats the text in a grid — across, then down, with even gaps — until the whole page is covered, so no corner of a screenshot escapes the mark. For the bottom strip it draws one small line of text centred near the bottom edge, like a printed footer. Because the watermark is real PDF content rather than a picture pasted on top, it prints with the document, survives forwarding, and shows in every reader — while your original pages are otherwise untouched, with text still selectable and images still sharp.
| Layout | Best for | Suggested opacity |
|---|---|---|
| Diagonal centre | DRAFT, CONFIDENTIAL, SAMPLE — status marks | 0.25 – 0.40 |
| Tiled grid | Notes, e-books, coaching material — ownership marks | 0.12 – 0.25 |
| Bottom strip | Your name or website on shared documents | 0.40 – 0.60 |
A watermark does two jobs at once. It warns — nobody can claim they did not know a quote was a draft — and it attributes: when a page is photographed, forwarded or printed, your name travels with it. Teachers watermark sample papers, freelancers watermark design drafts until payment lands, and coaching institutes watermark their notes so shared copies still advertise the source. Two minutes of stamping saves arguments that last much longer.
Worked example
A freelance designer, Sana, is sending a client a 6-page brand proposal as a PDF. Payment for this stage is still pending, so she wants every page marked, without making the designs hard to judge.
Step 1: She drops the proposal into the box — the tool confirms the file.
Step 2: In the text box she types DRAFT — Sana Designs.
Step 3: She keeps the diagonal layout, sets opacity to 0.25 so the artwork stays easy to see, size 48 pt, colour grey.
Step 4: She presses Add Watermark and sends the downloaded copy.
Every page now carries her name at a slant across the middle — visible in the client's reader, in prints and in any screenshot — while the proposal itself reads perfectly. Once payment clears, she sends the clean original from her own files, which never left her laptop.
FAQ
How do I add a watermark to a PDF?
Drop your PDF into the box, type the watermark text — a word like CONFIDENTIAL or DRAFT, or your name or business — choose the layout, opacity, size and colour, then press Add Watermark. A watermarked copy downloads with the text stamped on every page. Your original file is not changed, and nothing is uploaded.
Is my PDF uploaded to a server?
No. The watermark is drawn onto your pages entirely in your browser using the pdf-lib library stored on this website. Your document never leaves your device, so it is safe for contracts, invoices and ID documents.
Which layout should I choose — diagonal, tiled or bottom strip?
A single diagonal stamp across the middle is the classic choice for marking a document's status, like DRAFT or CONFIDENTIAL, and is hard to crop out. A tiled grid repeats the text over the whole page, which suits ownership marks on notes, e-books and study material. A bottom strip is a quiet footer — your name or website along the bottom edge — which suits sharing without shouting.
What opacity is best for a watermark?
Between 0.2 and 0.4 suits most documents: clearly visible, but the text underneath stays easy to read. Go lower, around 0.15, for a faint ownership mark on study notes, and higher, around 0.5, when the whole point is that nobody should mistake the document for a final copy.
Can a watermark be removed from my PDF?
A watermark drawn onto the page like this is part of the page content. Casual copying and screenshots will always carry it, and removing it cleanly is difficult, though a determined expert with editing tools may manage it on simple files. Treat a watermark as a strong deterrent and a proof of origin, not as encryption — password-protect the file too if the contents are truly sensitive.
Will the watermark cover or spoil my document?
No. The watermark is drawn as semi-transparent text over the page, and your original content is not redrawn or converted to images. Choose a modest opacity and size and the document stays perfectly readable — that balance is the whole idea of a watermark.