How to watermark a PDF
Text or image, set style, download.
Select a PDF
Drag a PDF onto the drop zone or click to pick one. The file is read into your browser memory and the configuration panel appears.
Configure the watermark
Choose Text or Image, pick font/size/color (or upload an image), set opacity (typical: 20–35%), rotation (−45° for a diagonal DRAFT mark), position, and which pages to stamp.
Apply & download
Click Apply watermark. pdf-lib stamps every targeted page in your browser and offers the new PDF as a download. The original is untouched and nothing was uploaded.
Why use Watermark PDF on imisspdf?
Private by architecture
The whole point of a watermark is often privacy: marking a draft, claiming ownership, or tracing a leak. Doing that on a server defeats the purpose. Here every byte stays in your browser — no upload, no log, no retention window.
Fast on any device
pdf-lib runs in WebAssembly and adds a watermark to every page in milliseconds per page. A 200-page contract finishes in a couple of seconds — no upload time, no queue.
Free, no signup
No daily limit, no signup, and zero watermark from us on your output. You control exactly what mark gets stamped, and only that mark appears.
Common questions about Watermark PDF
Yes. Switch the tab from Text to Image and upload a PNG or JPEG (PNG with transparency is best for logos so the page underneath shows through cleanly). Set the width as a percentage of the page width — 30–50% is typical for centered logos, 15–20% for corner stamps. Opacity and position controls apply the same way as for text watermarks. The image is embedded once in the PDF and reused on every page you target, so file-size overhead stays small even on long documents.
Once a watermark is applied here it is flattened into the page content stream — it becomes part of the page graphics, not a separate annotation, and there is no Undo from another tool that can pull it back out. If you still have the original PDF, re-process it from scratch. If you only have the watermarked copy, the only practical approaches are: (a) crop the page if the watermark sits in a margin, (b) use an inpainting tool on a rasterised page, or (c) try Adobe Acrobat Pro's "remove background" feature, which only works for watermarks added as Acrobat-style background objects, not flattened ones.
By default every page gets the watermark. Use the Pages field to target a subset: leave it blank (or type "all") for all pages, type "1-3" for the first three pages, "1,5,10" for individual pages, or combine them like "1-3,7,10-12". This is useful when you want a DRAFT mark only on the cover and table of contents, or only on signature pages. The range is parsed inclusively and ignores spaces.
No. The file is read into your browser memory by FileReader, then pdf-lib (running locally in WebAssembly) opens the PDF, draws the watermark on each targeted page, and serialises the result back to bytes — all inside the tab. You can confirm in DevTools: the Network panel shows zero outbound POST requests carrying your file. Because there is no server step, there is no server-side log, no temp file to subpoena, and no retention window to trust.
Not directly. If the PDF requires a password to open, pdf-lib will fail and you will get a "decrypt" error. Unlock it first using our Unlock PDF tool (in-browser, password stays in your tab), then come back here to watermark it. PDFs that are not password-locked but carry permission flags blocking modification will usually still watermark — pdf-lib ignores most non-encryption permission flags — but the resulting PDF may not be considered "permission-compliant" by strict readers. For PDF/A archival files, watermarking is allowed but the output is no longer a strict PDF/A — re-validate if you need to keep that status.
Text usually wins for legal and confidentiality marking — words like CONFIDENTIAL, DRAFT, or a recipient's name in plain letters are unambiguous to humans and to OCR. Image watermarks are best for branding (logos) and for marks that are hard to recreate (signatures, official seals). For traceable distribution — e.g. a contract sent to twelve reviewers where you want to know who leaked it — combine both: a centered text watermark with each recipient's name, plus your company logo in the corner. Keep opacity in the 20–35% range so the document stays readable but the watermark is unmissable.