A PDF watermark is text or an image overlaid on every page of a document to communicate its status, ownership, or distribution restrictions. Here is everything you need to know about PDF watermarks — and how to add or remove them for free.
A watermark is a semi-transparent text or image stamped onto PDF pages. It appears on every page and is typically set at reduced opacity (20–50%) so the underlying content remains readable. Common watermarks: CONFIDENTIAL, DRAFT, DO NOT COPY, SAMPLE, FOR REVIEW ONLY, company name, or a logo.
Text watermarks: the most common — plain text in any font, color, size, and rotation. Image watermarks: a logo or graphic placed on pages (usually as PNG with transparency). Diagonal watermarks: text rotated at 45° across the center — the classic "CONFIDENTIAL" style. Page-specific: applied only to sensitive pages rather than the whole document.
Draft documents sent for review (DRAFT — not for distribution). Contracts and legal documents shared for comment (FOR REVIEW ONLY). Sample documents given to prospects (SAMPLE). Internal documents that should not leave the organization (CONFIDENTIAL). Customer-specific documents with a personalized identifier to trace leaks.
Tip: For the highest tamper-resistance, flatten the PDF after watermarking (pdfeditor.onl/repair-pdf) to merge the watermark permanently into the page content layer.
Unflattenned watermarks are embedded as a PDF content element that can be edited by someone with PDF editing tools. Flattened watermarks (where the entire page is merged into a single content stream) are much harder to remove. For truly tamper-proof watermarks, flatten after watermarking.
No. A watermark is a visual element that communicates status or ownership. A digital signature is a cryptographic seal that verifies a document has not been altered since it was signed — a completely different technology.
The tool applies watermarks to all pages by default. For selective watermarking, split the PDF, watermark the target pages, then merge back.