Add a watermark to PDF — with a live preview on every page
Type your text, pick position, size, colour and rotation, and see it on every page before you download. Everything runs in your browser — your files never leave your device.
How to add a watermark to a PDF online
Adding a watermark with PDFluna takes about a minute and happens entirely in your browser. There is nothing to install, no account to create, and no files are sent to a remote server. Here is the full process, step by step:
- Upload your PDF. Drag and drop the PDF onto the upload area, or click Choose file. Files up to 100 MB are supported.
- Type your watermark text. Enter any text you want stamped onto every page — a word like DRAFT or CONFIDENTIAL, your name, a URL, or a date.
- Pick position, size, colour and rotation. Use the 3×3 grid to place the stamp (centre is the default). Pick a size, colour and tilt. Every setting repaints the preview live, so what you see on every thumbnail is exactly what the final file will look like.
- Apply and download. Click Apply watermark. The tool stamps every page locally in your browser and downloads a new PDF with the watermark baked in. Your original file is never modified.
Why people watermark PDFs
A watermark is an extra layer of text, usually faded or rotated, sitting on top of every page. Four jobs make up most of why people reach for one:
- Status markers. DRAFT, CONFIDENTIAL, NOT FOR DISTRIBUTION, INTERNAL USE ONLY. Readers see the status at a glance without opening the metadata or reading a cover letter.
- Ownership and attribution. Your name, your company, your URL stamped on every page so the document is identifiable after it gets forwarded, printed or screenshot.
- Tracking and copies. A dated stamp like Shared with John · 2024-05-12 gives you an audit trail without changing the document body — useful for NDAs and client deliverables.
- Deterrence. A visible watermark is a mild but real discouragement against sharing a PDF outside its intended audience. It does not stop a determined copier, but it raises the friction.
How PDFluna watermarks a PDF in your browser
Under the hood we use pdf-lib, an open-source JavaScript library for reading and writing PDFs. When you click Apply watermark, the tool loads your PDF into memory, walks every page, and draws your text on top with the position, size, rotation, colour and opacity you picked. Then it saves a new PDF and hands it to your browser for download. None of this touches our servers:
- Preview rendering. We open the PDF with PDF.js and render a thumbnail of every page. On top of each thumbnail sits a second transparent canvas that draws your watermark live — a single helper computes the placement for both the preview and the final file so they can never drift.
- Placement math. Every position in the 3×3 grid uses a 5% page-margin inset (clamped 24–60pt) so the text never touches the edge of A4 or Letter. Size is in PDF points (1 pt = 1/72"), so a 72pt letter is roughly one inch tall regardless of the document's physical page dimensions.
- Font embedding. The five supported fonts are pdf-lib's StandardFonts, which are built into every PDF reader. No font bytes are fetched over the network, and the resulting PDF stays as small as possible.
- Output. The watermark is written as real text in the PDF, not a raster overlay, so it stays crisp at any zoom level and prints perfectly. Your original page content is preserved unchanged underneath.
Is it safe to watermark a PDF online?
With PDFluna, yes — because nothing is actually "online" about the watermarking step. Once the page has loaded in your browser, the PDF is read into memory using the standard File API and processed with JavaScript on your own machine. We never upload it, never see it and never store it. That makes PDFluna a safe choice for stamping confidential drafts, signed contracts, medical forms or private records. You can verify the privacy claim yourself: open browser DevTools, switch to the Network tab, and watch while you apply a watermark — you will see zero uploads.
Tips for a watermark that actually looks good
- Start with 30% opacity. Below 20% the stamp disappears on coloured backgrounds. Above 50% it fights with the content for attention. The default 30% is a sweet spot for most documents.
- Rotate by −45° for the classic DRAFT look. Diagonal text reads as "watermark" instinctively and covers more of the page area than a straight line.
- Use grey, not black, for subtle stamps. Black at 30% opacity still reads as "emphasis"; grey at 30% reads as "watermark" — the brain parses it as background texture.
- Pick size L (72pt) for centre-page stamps. Smaller sizes vanish when printed; bigger sizes obscure content. 72pt fits a one-word stamp across A4 without wrapping.
- Edge positions for ownership, centre for status. Use top-left or bottom-right for signatures, URLs and copyright marks; use the centre 9-position for DRAFT / CONFIDENTIAL / WATERMARK banners.
Frequently asked questions
Does my PDF leave my browser?
No. The watermark is drawn on every page using pdf-lib running in your browser. Nothing is uploaded to a server. You can verify this yourself by opening DevTools → Network tab while the tool runs — no file transfer happens. That makes it safe to watermark confidential drafts, contracts, NDAs or personal documents.
What does the preview on every page show me?
Exactly what the final PDF will contain. Every thumbnail renders the original page with your watermark overlaid at the real position, size, rotation, colour and opacity. Because page sizes can differ inside one document (mixed portrait and landscape, for example), seeing the watermark on every page beforehand matters — a 30% opacity grey diagonal may look perfect on a tall portrait and slightly clipped on a wide landscape, and you catch that before downloading.
Can I put the watermark behind the content instead of on top?
In this version, the watermark is drawn on top of the page content with the opacity you pick. Most users want 20–40% opacity so the text stays readable through the stamp — that reads visually as "behind" the content even though technically it is on top. A true back-layer ("watermark under content") mode is planned for a later update.
Can I use a logo image instead of text?
Not in this version. Text watermarking ships first because it covers 90% of real-world use (DRAFT, CONFIDENTIAL, names, dates). Image watermarks are on the roadmap.
Which fonts can I use, and does it support Cyrillic / Ukrainian / Greek text?
Yes. For Latin text the tool uses five standard PDF fonts — Helvetica, Helvetica Bold, Times Roman, Times Roman Bold and Courier — which are built into every PDF reader, so the file displays identically everywhere without embedding fonts. If your watermark contains non-Latin characters (Cyrillic, Ukrainian, Greek, etc.) the tool automatically embeds Lato, an open-source Unicode font, so those glyphs render correctly in the output. The substitution happens silently the first time you type non-Latin text; subsequent pages in the same document use the same embedded font.
Should I use Single or Pattern mode?
Single places one stamp per page at the position you pick on the 3×3 grid — best for a subtle status label (DRAFT in the centre) or an ownership mark in a corner. Pattern tiles the stamp across the whole page in a diagonal grid — harder to remove or crop out, best for strong deterrence on confidential drafts and preview copies. You can switch between them at any time and the preview updates live on every page so you can compare before you download.
Will the watermark appear if someone prints the PDF?
Yes. The watermark is baked into the page content, not added as a viewer-only overlay, so it prints, exports, screenshots and forwards along with the rest of the document.
Can I remove a watermark later?
The watermark becomes part of the PDF's page content, so it's permanent on this output file. To get an un-watermarked version, re-upload your original and skip the watermark step. Keep a copy of the original if you might need it later.
What happens to pages that are rotated 90°/180°/270°?
In this first version the watermark is positioned in the page's stored coordinate system, so on pages with a baked rotation the stamp may appear rotated or repositioned. If every page in your file has the same orientation, results are as expected. Full rotated-page support is coming in an update — use our free Rotate PDF tool first if your scan has pages at the wrong angle.