PDF Watermark
Protect your intellectual property. Free, in your browser.
.pdf · up to 100 MB
Why use it
Protect your PDFs with a watermark
Full control
Set text, opacity, size, angle, and position. Watermark applied to every page.
100% private
Your PDF is processed in your browser. Never uploaded to any server.
Professional quality
Watermark embedded in the PDF annotation layer, not just overlaid on screen.
Instant
Results in seconds, no waiting for server-side processing queues.
How it works
Three steps, no hassle
Upload your PDF
Drag or select your PDF file. It's processed in your browser, never uploaded to any server.
Configure the watermark
Enter text, adjust opacity (20–40% recommended), size, position, and angle.
Download your watermarked PDF
The resulting PDF includes the watermark on all pages. Download with one click.
FAQ
Got questions?
A watermark is a visual overlay on top of PDF content. It can be text (such as 'CONFIDENTIAL' or 'DRAFT') or a semi-transparent image. Unlike steganographic watermarks (invisible, used for forensic tracking), visible watermarks deter unauthorized use of the document.
The optimal range is 20–40% opacity. Below 15% the watermark is barely visible; above 50% it can impede reading the underlying text. For 'DRAFT' or 'CONFIDENTIAL' documents, 25–35% is recommended.
Tiled watermarks (repeated across the page) offer stronger document control: they cover every section, making it harder to crop or edit parts of the PDF. A centered watermark is more subtle and suitable for presentation documents. For maximum security, use a diagonal tile pattern.
Visible watermarks can be removed with advanced PDF editors (Adobe Acrobat, PDFescape) if the PDF isn't password-protected. However, they deter the casual user. Invisible (steganographic) watermarks are much harder to remove without degrading the document.
Watermarks are especially useful for: drafts sent for review ('DRAFT', 'DO NOT DISTRIBUTE'), business proposals ('CONFIDENTIAL'), educational materials ('AUTHORIZED USE ONLY'), legal documents pending signature ('COPY INVALID'), and reports sent to multiple recipients to trace leaks.
Watermarks in documents: history and technique
Watermarks originated in the paper mills of the 13th century. The Fabriano papermill (Italy) introduced them around 1282 to identify the origin and quality of paper: filigrees were created by deforming the wire mesh of the mold so the paper was thinner in that area, making a design visible when held up to light. This authentication technique persisted for centuries and is the basis of banknote security today.
In the digital world, PDFs use the annotation layer defined by ISO 32000 to overlay content without modifying the original document content. A watermark can be implemented as a stamp annotation or directly as content in the page content stream. ISO 32000-1 and its revision ISO 32000-2 (PDF 2.0) define the transparency, blend modes, and opacity parameters that enable professional-looking watermarks.
From a legal perspective, a visible watermark on a document does not have standalone legal value in most jurisdictions, but it can serve as evidence that the recipient was aware of the document's confidential nature, strengthening arguments in information leak cases. For robust legal protection, combine a visible watermark with authorship metadata and, where applicable, a certified digital signature.